UNIVERSITY  OF  CALIFORNIA 
AT  LOS  ANGELES 


GIFT   OF   CAPT.   AND   MRS. 
PAUL  MCBRIDE  PERIGORD 


UNIVERSITY  of  CALIFORNIA 

AT 

LOS  ANGELES 
LIBRARY 


•   ? 


33|j  professor  $L  IE,  JMfcear 


MATTER,  ETHER  AND  MOTION 

The  Factors  and  Relations  of  Physical  Science 
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MODES  OF  MOTION 


MECHANICAL  CONCEPTIONS 

OF 

PHYSICAL  PHENOMENA 


BY 

A.  E.  DOLBEAR 

PROFESSOR   OF    1'HYSICS,    TUFTS   COLLEGE 


AUTHOR  OF    'THE  ART  OK  TKOJF.CTING"  "MATTER,  ETHER,  AND 
MOTION"  "THIS  TELEPHONE "  ETC. 


BOSTON 
LEE  AND  SHEPARD  PUBLISHERS 

IO    MILK     STREET 

1897 


135952 


COPYRIGHT,  1897,  BY  LEE  AND  SHEPARD 


All  Rights  Reserved 


MODES  OF  MOTION 


TYPOGRAPHY    BY   C.   J.    PETERS   &  SON,    BOSTON. 
PRBSSWORK    BY    BERWICK    &   SMITH. 


GtC 


3 


TABLE   OF   CONTENTS 


CHAPTER   I 

PAGE 

V        Ideas  of  Phenomena,  ancient  and  modern,  metaphysical 

y^                 and  mechanical 1-3 

^         Imponderables 4 

Forces,  invented  and  discarded 5 

Explanations 7 

Energy,  its  Factors,  Kinetic  and  Potential 8 

^         Motion,  kinds  and  transformations  of 10 

y        Mechanical,  Molecular  and  Atomic II 

V»         Invention  of  Ethers,  Faraday's  Conceptions       ....  15 

CHAPTER   II 

V)         Properties  of  Matter  and  Ether  compared 19 

f         Discontinuity  vs.  Continuity 21 

o^       Size  of  Atoms,  Astronomical  Distances 22 

\        Number  of  Atoms  in  Universe 23 

^         Ether  unlimited 24 

>         Different  Kinds  of  Matter,  permanent  qualities  of  ...  26 
L          Atomic  Structure.     Vortex  Rings,  their  Properties       .      28-31 

T)         Ether  Structureless 32 

Matter  Gravitative,  Ether  not 33>  34 

Friction  in  Matter,  Ether  Frictionless 35,  36 

Chemical  Properties 40 

Energy  in  Matter  and  in  Ether 45 

Matter  as  a  Transformer  of  Energy 46 

iii 


IV  TABLE   OF  CONTENTS 

PAGE 

Elasticity ' 49 

Vibratory  Rates  and  Waves 52 

Density 54 

Heat 57 

Indestructibility  of  Matter ,....  61 

Inertia  in  Matter  and  in  Ether 65 

Matter  not  inert 71 

Magnetism  and  Ether  Waves 73,  74 

States  of  Matter 80 

Cohesion  affected  by  Temperature 81 

Shearing  Stress  in  Solids  and  in  Ether 83,  84 

Ether  Pressure 84 

Sensation  dependent  upon  Matter 85 

Nervous  system  not  affected  by  Ether  .     ...     .     .     .  87 

Other  Stresses  in  the  Ether 89 

CHAPTER     III 

Transformations  of  Motion 92 

Terminology 93 

Antecedents  of  Electricity ..;...  96 

Nature  of  what  is  transformed 104 

Series  of  Transformations  for  the  Production  of  Light      .  105 

Positive  and  Negative  Electricity     .........  106 

Positive  and  Negative  Twists .     .     .  107 

Rotation  of  Arc .  108 

Rotations  about  a  Wire 109 

Ether  a  Non-conductor 112 

Electro-magnetic  Waves 115 

Ether  Stress  and  Atomic  Position    .     .     . 115 

Induction  and  inductive  Action .     .     .  116 

Nature  of  an  Electric  Current 118 

Electricity  a  Condition,  not  an  Entity 119 


MODES  OF  MOTION; 

OR, 

Mechanical  Conceptions  of  Physical  Phenomena 


CHAPTER    I 

And  now  we  might  add  something  concerning  a  most  subtile  spirit 
which  pervades  and  lies  hid  in  all  gross  bodies,  by  the  force  and  ac- 
tion of  which  spirit  the  particles  of  bodies  attract  each  other  at  near 
distances,  and  cohere  if  contiguous,  and  electric  bodies  operate  at 
greater  distances  as  well  repelling  as  attracting  neighboring  corpus- 
cles, and  light  is  emitted,  reflected,  inflected  and  heats  bodies,  and  all 
sensation  is  excited  and  members  of  animal  bodies  move  at  the  com- 
mand of  the  will.  NEWTON,  in  Principia. 

IN  Newton's  day  the  whole  field  of  nature 
was  practically  lying  fallow.  No  fundamental 
principles  were  known  until  the  law. of  gravita- 
tion was  discovered.  This  law  was  behind  all 
the  work  of  Copernicus,  Kepler,  and  Galileo  ; 
and  what  they  had  done  needed  interpretation. 
It  was  quite  natural  that  the  most  obvious  and 
mechanical  phenomena  should  first  be  reduced  ; 
and  so  the  Principia  was  concerned  with  me- 
chanical principles  applied  to  astronomical  prob- 


2  MODES  OF  MOTION 

lems.  To  us,  who  have  grown  up  familiar  with 
the  principles  and  conceptions  underlying  them, 
all  varieties  of  mechanical  phenomena  seem  so 
obvious  that  it  is  difficult  for  us  to  under- 
stand how  any  one  could  be  obtuse  to  them  ;  but 
the  records  of  Newton's  time,  and  immediately 
after  this,  show  that  they  were  not  so  easy  of 
apprehension.  It  may  be  remembered  that  they 
were  not  adopted  in  France  till  long  after  New- 
ton's day.  In  spite  of  what  is  thought  to  be 
reasonable,  it  really  requires  something  more 
than  complete  demonstration  to  convince  most 
of  us  of  the  truth  of  an  idea,  should  the  truth 
happen  to  be  of  a  kind  not  familiar,  or  should 
it  chance  to  be  opposed  to  our  more  or  less 
well-defined  notions  of  what  it  is  or  ought  to 
be.  If  those  who  labor  for  and  attain  what 
they  think  to  be  the  truth  of  any  matter  were 
a  little  better  informed  about  mental  processes 
and  the  conditions  under  which  ideas  grow  and 
displace  others,  they  would  be  more  patient  with 
mankind;  and  teachers  of  every  rank  might  dis- 
cover that  what  is  often  called  stupidity  may  be 
no  more  than  mental  inertia,  which  can  no  more 
be  made  active  by  willing  than  can  the  move- 
ment of  a  cannon-ball  by  a  like  effort.  We  grow 
into  our  beliefs  and  opinions  upon  all  matters, 
and  scientific  ideas  are  no  exceptions. 

Whewell,  in  his  History  of  the  Inductive  Sci- 


IDEAS   OF  PHENOMENA  3 

ences,  says  that  the  Greeks  made  no  headway  in 
physical  science,  because  they  lacked  appropri- 
ate ideas.  The  evidence  is  overwhelming  that 
they  were  as  observing,  as  acute,  as  reasonable, 
as  any  who  live  to-day.  With  this  view,  it 
would  appear  that  the  great  discoverers  must 
have  been  men  who  started  out  with  appropri- 
ate ideas  —  were  looking  for  what  they  found. 
If,  then,  one  reflects  upon  the  exceeding  great 
difficulty  there  is  in  discovering  one  new  truth, 
and  the  immense  amount  of  work  needed  to 
disentangle  it,  it  would  appear  as  if  even  the 
most  successful  have  but  indistinct  ideas  of 
what  is  really  appropriate,  and  that  their  me- 
chanical conceptions  become  clarified  by  doing 
their  work.  This  is  not  always  the  fact.  In 
the  statement  of  Newton  quoted,  he  speaks  of 
a  spirit  which  lies  hid  in  all  gross  bodies,  etc., 
by  means  of  which  all  kinds  of  phenomena  are 
to  be  explained  :  but  he  deliberately  abandons 
that  idea  when  he  comes  to  the  study  of  light, 
for  he  assumes  the  existence  and  activity  of 
light  corpuscles,  for  which  he  has  no  experi- 
mental evidence ;  and  the  probability  is  that  he 
did  this  because  the  latter  conception  was  one 
which  he  could  handle  mathematically,  while  he 
saw  no  way  for  thus  dealing  with  the  other. 
His  mechanical  instincts  were  more  to  be 
trusted  than  his  carefully  calculated  results  ; 


4  MODES  OF  MOTION 

for,  as  all  know,  what  he  called  "  spirits  "  is 
what  to-day  we  call  the  ether,  and  the  corpus- 
cular theory  of  light  has  now  no  more  than  an 
historic  interest.  The  corpuscular  theory  was 
a  mechanical  conception,  but  each  such  corpus- 
cle was  ideally  endowed  with  qualities  which 
were  out  of  all  relations  with  the  ordinary  mat- 
ter with  which  it  was  allied. 

Until  the  middle  of  the  present  century  the 
reigning  physical  philosophy  held  to  the  exist- 
ence of  what  were  called  imponderables.  The 
phenomena  of  heat  were  explained  as  due  to  an 
imponderable  substance  called  "caloric,"  which 
ordinary  matter  could  absorb  and  emit.  A  hot 
body  was  one  which  had  absorbed  an  imponder- 
able substance.  It  was,  therefore,  no  heavier 
than  before,  but  it  possessed  ability  to  do  work 
proportional  to  the  amount  absorbed.  Carnot's 
ideal  engine  was  described  by  him  in  terms  that 
imply  the  materiality  of  heat.  Light  was  an- 
other imponderable  subtance  maintained  by  Sir 
David  Brewster  as  long  as  he  lived.  Electricity 
and  magnetism  were  imponderable  fluids,  which, 
when  allied  with  ordinary  matter,  endowed  the 
latter  with  their  peculiar  qualities.  The  con- 
ceptions in  each  case  were  properly  mechanical 
ones  part  (but  not  all)  of  the  time  ;  for  when 
the  immaterial  substances  were  dissociated  from 
matter,  where  they  had  manifested  themselves, 


PHYSICAL   FORCES  5 

no  one  concerned  himself  to  inquire  as  to  their 
whereabouts.  They  were  simply  off  duty,  but 
could  be  summoned,  like  the  genii  in  the  story 
of  Aladdin's  Lamp.  Now,  a  mechanical  con- 
ception of  any  phenomenon,  or  a  mechanical 
explanation  of  any  kind  of  action,  must  be  me- 
chanical all  the  time,  the  antecedents  as  well  as 
the  consequents.  Nothing  else  will  do  except 
a  miracle. 

During  the  fifty  years  from  about  1820  to 
1870,  a  somewhat  different  kind  of  explanation 
of  physical  events  grew  up.  The  interest  that 
was  aroused  by  the  discoveries  in  all  the  fields 
of  physical  science  —  in  heat,  electricity,  mag- 
netism, and  chemistry  —  by  Faraday,  Joule, 
Helmholtz,  and  others,  compelled  a  change  of 
conceptions :  for  it  was  noticed  that  each  special 
kind  of  phenomenon  was  preceded  by  some 
other  definite  and  known  kind ;  as,  for  instance, 
that  chemical  action  preceded  electrical  cur- 
rents, that  mechanical  or  electrical  activity  re- 
sulted from  changing  magnetism,  and  so  on. 
As  each  kind  of  action  was  believed  to  be  due 
to  a  special  force,  there  were  invented  such 
terms  as  mechanical  force,  electrical  force,  mag- 
netic, chemical,  and  vital  forces ;  and  these  were 
discovered  to  be  convertible  into  one  another, 
and  the  "doctrine  of  the  correlation  of  the  phys- 
ical forces  "  became  a  common  expression  in 


6  MODES  OF  MOTION 

philosophies  of  all  sorts.  By  "  convertible  into 
one  another"  was  meant,  that,  whenever  any 
given  force  appeared,  it  was  at  the  expense  of 
some  other  force  :  thus,  in  a  battery,  chemical 
force  was  changed  into  electrical  force  ;  in  a 
magnet,  electrical  force  was  changed  into  mag- 
netic force,  and  so  on.  The  idea  here  was  the 
transformation  of  forces ;  and  forces  were  not  so 
clearly  denned  that  one  could  have  a  mechani- 
cal idea  of  just  what  had  happened.  That  part 
of  the  philosophy  was  no  clearer  than  that  of  the 
imponderables  which  had  largely  dropped  out 
of  mind.  The  terminology  represented  an  ad- 
vance in  knowledge,  but  was  lacking  in  lucidity, 
for  no  one  knew  what  a  force  of  any  kind  was. 
The  first  to  discover  this  and  to  repudiate  it 
were  the  physiologists,  who  early  announced 
their  disbelief  in  a  vital  force,  and  their  belief 
that  all,  physiological  activities  were  of  purely 
physical  and  chemical  origin,  and  that  there 
was  no  need  to  assume  any  such  thing  as  a 
vital  force.  Then  came  the  discovery  that 
chemical  force,  or  affinity,  had  only  an  adventi- 
tious existence,  and  that  at  absolute  zero  there 
was  no  such  activity.  The  discovery  of,  or 
rather  the  appreciation  of,  what  is  implied  by 
the  term  absolute  zero,  and  especially  of  the 
nature  of  heat  itself,  as  expressed  in  the  state- 
ment that  heat  is  a  mode  of  motion,  dismissed 


EXPLANA  TIONS  7 

another  of  the  so-called  forces  as  being  a  meta- 
physical agency  having  no  real  existence,  though 
standing  for  phenomena  needing  further  atten- 
tion and  explanation  ;  and  by  explanation  is 
meant  the  presentation  of  the  mechanical  antece- 
dents for  a  phenomenon,  in  so  complete  a  way 
that  no  supplementary  or  unknown  factors  are 
necessary.  The  train  moves  because  the  engine 
pulls  it  ;  the  engine  pulls  because  the  steam 
pushes  it.  There  is  no  more  necessity  for  as- 
suming a  steam  force  between  the  steam  and 
the  engine,  than  for  assuming  an  engine  force 
between  the  engine  and  the  train.  All  the 
processes  are  mechanical,  and  have  to  do  only 
with  ordinary  matter  and  its  conditions,  from 
the  coal-pile  to  the  moving  freight,  though 
there  are  many  transformations  of  the  forms  of 
motion  and  of  energy  between  the  two  ex- 
tremes. 

During  the  past  thirty  years  there  has  come 
into  common  use  another  term,  unknown  in 
any  technical  sense  before  that  time ;  namely, 
energy.  What  was  once  called  the  conserva- 
tion of  force  is  now  called  the  conservation  of 
energy,  and  we  now  often  hear  of  forms  of  en- 
ergy. Thus,  heat  is  said  to  be  a  form  of  energy  ; 
and  the  forms  of  energy  are  convertible  into 
one  another,  as  the  so-called  forces  were  for- 
merly supposed  to  be  transformable  into  one 


8  MODES  OF  MOTION 

another.  We  are  asked  to  consider  gravitative 
energy,  heat  energy,  mechanical  energy,  chem- 
ical energy,  electrical  energy.  When  we  in- 
quire what  is  meant  by  energy,  we  are  informed 
that  it  means  ability  to  do  work,  and  that  work 
is  measurable  as  a  pressure  into  a  distance,  and 
is  specified  as  foot-pounds.  A  mass  of  matter 
moves  because  energy  has  been  spent  upon  it, 
and  has  acquired  energy  equal  to  the  work 
done  on  it ;  and  this  is  believed  to  hold  true, 
no  matter  what  the  kind  of  energy  was  that 
moved  it.  If  a  body  moves,  it  moves  because 
another  body  has  exerted  pressure  upon  it,  and 
its  energy  is  called  kinetic  energy ;  but  a  body 
may  be  subject  to  pressure,  and  not  move  ap- 
preciably, and  then  the  body  is  said  to  possess 
potential  energy.  Thus,  a  bent  spring  and  a 


A 


Fig.  1. 

raised  weight  are  said  to  possess  potential  en- 
ergy. In  either  case,  an  energized  body  receives 
its  energy  by  pressure,  and  has  ability  to  produce 
pressure  on  another  body.  Whether  or  not  it 
does  work  on  another  body  depends  on  the 


MECHANICAL    MOTIONS  9 

rigidity  of  the  body  it  acts  upon.  In  any  case, 
it  is  simply  a  mechanical  action,  —  body  A 
pushes  upon  body  B  (Fig.  i).  There  is  no 
need  to  assume  anything  more  mysterious  than 
mechanical  action.  Whether  body  B  moves 
this  way  or  that  depends  upon  the  direction  of 
the  push,  the  point  of  its  application.  Whether 
the  body  be  a  mass  as  large  as  the  earth  or  as 
small  as  a  molecule  makes  no  difference  in 
that  particular.  Suppose,  then,  that  a  (Fig.  2) 


Fig.  2. 

spends  its  energy  on  b,  b  on  c,  c  on  d,  and  so 
on.  The  energy  of  a  gives  translatory  motion 
to  b,  b  sets  c  vibrating,  and  c  makes  d  spin  on 
some  axis.  Each  of  these  has  had  energy  spent 
on  it,  and  each  has  some  form  of  energy  differ- 
ent from  the  other ;  but  no  new  factor  has  been 
introduced  between  a  and  d,  and  the  only  fac- 
tor that  has  gone  from  a  to  d  has  been  motion, 
—  motion  that  has  had  its  direction  and  quality 
changed,  but  not  its  nature.  If  we  agree  that 
energy  is  neither  created  nor  annihilated  by 
any  physical  process,  and  if  we  assume  that  a 
gave  to  b  all  its  energy, — that  is,  all  its  motion, 


10  MODES   OF  MOTION 

—  that  b  likewise  gave  its  all  to  c,  and  so  on, 
then  the  succession  of  phenomena  from  a  to  d 
has  been  simply  the  transferrence  of  a  definite 
amount  of  motion,  and  therefore  of  energy, 
from  the  one  to  the  other  ;  for  motion  has  been 
the  only  variable  factor.  If,  furthermore,  we 
should  agree  to  call  the  translatory  motion  a, 
the  vibratory  motion  (3,  the  rotary  y,  then  we 
should  have  had  a  conversion  of  a  into  ft,  of  ft 
into  y  (Fig-  2).  If  we  should  consider  the 
amount  of  the  transferrence  instead  of  the  kind 
of  motion,  we  should  have  to  say  that  the  a 
energy  had  been  transformed  into  ft,  and  the 
ft  into  y. 

What  a  given  amount  of  energy  will  do  de- 
pends only  upon  its  form;  that  is,  the  kind  of 
motion  that  embodies  it. 

The  energy  spent  upon  a  stone  thrown  into 
the  air,  giving  it  translatory  motion,  would,  if 
spent  upon  a  tuning-fork,  make  it  sound,  but 
not  move  from  its  place  ;  while  if  spent  upon  a 
top,  would  enable  the  latter  to  stand  upon  its 
point  as  easily  as  a  person  stands  on  his  two 
feet,  and  to  do  other  surprising  things  which 
otherwise  it  could  not  do.  One  can,  without 
difficulty,  form  a  mechanical  conception  of  the 
whole  series  without  assuming  imponderables 
or  fluids  or  forces.  Mechanical  motion  only, 
by  pressure,  has  been  transferred  in  certain  di- 


IMPRESSING  MOTION  II 

rections  at  certain  rate's.     Suppose,  now,  that 
some  one  should  suddenly  come  upon  a  spin- 
ning top  (Fig.   3)  while  it  was  standing  upon 
its  point,  and,  as  its  mo- 
tion might  not  be  visible, 
should  cautiously  touch  it. 
It  would  bound  away  with 
surprising     promptness  ; 
and,   if    he   were   not    in- 
structed in  the   mechani- 
cal principles  involved,  he 
might  fairly  well  draw  the 
conclusion  that  it  was  ac- 
tuated by  other  than  sim- 
ple mechanical  principles  ; 

and,  for  that  reason,  it  would  be  difficult  to  per- 
suade him  that  there  was  nothing  essentially  dif- 
ferent in  the  body  that  appeared  and  acted  thus, 
than  in  a  stone  thrown  into  the  air  :  neverthe- 
less, that  statement  would  be  the  simple  truth. 
All  of  our  experience,  without  a  single  ex- 
ception, enforces  the  proposition  that  no  body 
moves  in  any  direction,  or  in  any  way,  except 
when  some  other  body  in  contact  with  it  im- 
presses its  own  motion  upon  it.  The  action  is 
direct.  In  Newton's  letter  to  his  friend  Bent- 
ley,  he  says  :  "  That  one  body  should  act  upon 
another  through  empty  space,  without  the  me- 
diation of  anything  else  by  and  through  which 


12  MODES  OF  MOTION 

their  action  and  pressure  may  be  conveyed  from 
one  to  another  is  to  me  so  great  an  absurdity 
that  I  believe  no  man  who  has  in  philosophical 
matters  a  competent  faculty  of  thinking  can 
ever  fall  into  it." 

For  mathematical  purposes,  it  has  sometimes 
been  convenient  to  treat  a  problem  as  if  one 
body  could  act  upon  another  without  any  phys- 
ical medium  between  them  ;  but  such  a  con- 
ception has  no  degree  of  rationality,  and  I  know 
of  no  one  who  believes  in  that  as  a  fact.  If 
this  be  granted,  then  our  philosophy  agrees 
with  our  experience,  and  every  body  moves 
because  it  is  pushed,  and  the  mechanical  ante- 
cedent of  every  kind  of  phenomenon  is  to  be 
looked  for  in  some  adjacent  body  possessing 
energy ;  that  is,  the  ability  to  push  or  produce 
pressure. 

It  must  not  be  forgotten  that  energy  is  not  a 
simple  factor,  but  is  always  a  product  of  two 
factors,  —  a  mass  with  a  velocity,  a  mass  with 
a  temperature,  a  quantity  of  electricity  into  a 
pressure,  and  so  on.  One  may  sometimes  meet 
the  statement  that  matter  and  energy  are  the 
two  realities  ;  both  are  spoken  of  as  entities. 
It  is  much  more  philosophical  to  speak  of  mat- 
ter and  motion :  for  in  the  absence  of  motion 
there  is  no  energy,  and  the  energy  varies  with 
the  amount  of  motion  ;  and,  furthermore,  to 


ALL   ENERGY  KINETIC  13 

understand  any  manifestation  of  energy  one 
must  inquire  what  kind  of  motion  is  involved. 
This  we  do  when  we  speak  of  mechanical  en- 
ergy as  the  energy  involved  in  a  body  having 
a  translatory  motion ;  also,  when  we  speak  of 
heat  as  a  vibratory,  and  of  light  as  a  wave,  mo- 
tion. To  speak  of  energy  without  stating  or 
implying  these  distinctions  is  to  speak  loosely, 
and  to  keep  far  within  the  bounds  of  actual 
knowledge.  To  speak  thus  of  a  body  possess- 
ing energy  or  expending  energy,  is  to  imply 
that  the  body  possesses  some  kind  of  motion, 
and  produces  pressure  upon  another  body  be- 
cause it  has  motion.  Tait  and  others  have 
pointed  out  the  fact  that  what  is  called  poten- 
tial energy  must,  in  its  nature,  be  kinetic.  He 
says  :  "  Now  it  is  impossible  to  conceive  of  a 
truly  dormant  form  of  energy  whose  magnitude 
should  depend,  in  any  way,  upon  the  unit  of 
time ;  and  we  are  forced  to  conclude  that  po- 
tential energy,  like  kinetic  energy,  depends 
(even  if  unexplained  or  unimagined)  upon  mo- 
tion." All  this  means  that  it  is  now  too  late 
to  stop  with  energy  as  a  final  factor  in  any  phe- 
nomenon ;  that  the  form  of  motion  which  em- 
bodies the  energy  is  the  factor  that  determines 
ivhat  happens,  as  distinguished  from  how  much 
happens.  Here,  then,  are  to  be  found  the  dis- 
tinctions which  have  heretofore  been  called 


14  MODES  OF  MOTION 

forces;  here  is  embodied  the  proof  that  direct 
pressure  of  one  body  upon  another  is  what 
causes  the  latter  to  move,  and  that  the  direc- 
tion of  movement  depends  on  the  point  of  ap- 
plication, with  reference  to  the  centre  of  mass. 

It  is  needful  now  to  look  at  the  other  term  in 
the  product  we  call  energy ;  namely,  the  sub- 
stance moving,  sometimes  called  matter  or  mass. 
It  has  been  mentioned  that  the  idea  of  a  medium 
filling  space  was  present  with  Newton  ;  but  his 
gravitation  problem  did  not  require  that  he 
should  consider  other  factors  than  masses  and 
distances.  The  law  of  gravitation  as  considered 
by  him  was :  "  Every  particle  of  matter  attracts 
every  other  particle  of  matter  with  a  stress 
which  is  proportional  to  the  product  of  their 
masses,  and  inversely  as  the  square  of  the 
distance  between  them."  Here  we  are  con- 
cerned only  with  the  statement  that  every  par- 
ticle of  matter  attracts  every  other  particle  of 
matter.  Everything,  then,  that  possesses  gravi- 
tative  attraction  is  matter  in  the  sense  in  which 
that  term  is  used  in  this  law.  If  there  be  any 
other  substance  in  the  universe  that  is  not  thus 
subject  to  gravitation,  then  it  is  improper  to 
call  it  matter,  otherwise  the  law  should  read  : 
"  Some  particles  of  matter  attract,"  etc.,  which 
will  never  do. 

We  are  now  assured  that  there  is  something 


LUMINIFEROUS  ETHER  15 

else  in  the  universe  which  has  no  gravitative 
property  at  all ;  namely,  the  ether.  It  was  first 
imagined  in  order  to  account  for  the  phenomena 
of  light,  which  was  observed  to  take  about 
eight  minutes  to  come  from  the  sun  to  the 
earth.  Then  Young  applied  the  wave  theory 
to  the  explanation  of  polarization  and  other 
phenomena;  and,  in  1851,  Foucault  proved  ex- 
perimentally that  the  velocity  of  light  was  less 
in  water  than  in  air,  as  it  should  be  if  the  wave 
theory  be  true ;  and  this  has  been  considered 
a  crucial  experiment  which  took  away  the  last 
hope  for  the  corpuscular  theory,  and  demon- 
strated the  existence  of  the  ether  as  a  space- 
filling medium  capable  of  transmitting  light- 
waves known  to  have  a  velocity  of  186,300 
miles  per  second.  It  was  called  the  luminifer- 
ous  ether,  to  distinguish  it  from  other  ethers 
which  had  also  been  imagined,  such  as  electric 
ether  for  electrical  phenomena,  magnetic  ether 
for  magnetic  phenomena,  and  so  on  —  as  many 
ethers  as  there  were  different  kinds  of  phenom- 
ena to  be  explained. 

It  was  Faraday  who  put  a  stop  to  the  inven- 
tion of  ethers,  by  suggesting  that  the  so-called 
luminiferous  ether  might  be  the  one  concerned 
in  all  the  different  phenomena,  and  who  pointed 
out  that  the  arrangement  of  iron  filings  about  a 
magnet  was  indicative  of  the  direction  of  the 


1 6  MODES  OF  MOTION 

stresses  in  the  ether.  This  suggestion  did  not 
meet  the  approval  of  the  mathematical  physi- 
cists of  his  day ;  for  it  necessitated  the  abandon- 
ment of  the  conceptions  they  had  worked  with, 
as  well  as  the  terminology  which  had  been  em- 
ployed, and  made  it  needful  to  reconstruct  all 
their  work  to  make  it  intelligible,  —  a  labor 
which  was  the  more  distasteful  as  it  was  forced 
upon  them  by  one  who,  although  expert  enough 
in  experimentation,  was  not  a  mathematician, 
and  who  boasted  that  the  most  complicated 
mathematical  work  he  ever  did  was  to  turn  the 
crank  of  a  calculating-machine ;  who  did  all  his 
work,  formed  his  conclusions,  and  then  said  : 
"The  work  is  done;  hand  it  over  to  the  com- 
puters." 

It  has  turned  out  that  Faraday's  mechanical 
conceptions  were  right.  Every  one  now  knows 
of  Maxwell's  work,  which  was  to  start  with 
Faraday's  conceptions  as  to  magnetic  phenom- 
ena, and  follow  them  out  to  their  logical  conclu- 
sions, applying  them  to  molecules  and  their 
reactions  upon  the  ether.  Thus  he  was  led  to 
conclude  that  light  was  an  electro-magnetic 
phenomenon ;  that  is,  that  the  waves  which 
constitute  light  and  waves  produced  by  chan- 
ging magnetism  were  identical  in  their  nature, 
were  in  the  same  medium,  travelled  with  the 
same  velocity,  were  capable  of  refraction,  and 


ETHER    WAVES  I? 

so  on.  Now  that  all  this  is  a  matter  of  com- 
mon knowledge  to-day,  it  is  curious  to  look 
back  no  farther  than  ten  years.  Maxwell's 
conclusions  were  adopted  by  scarcely  a  physi- 
cist in  the  world.  Although  it  was  known  that 
inductive  action  travelled  with  finite  velocity  in 
space,  and  that  an  electro-magnet  would  affect 
the  space  about  it  practically  inversely  as  the 
square  of  the  distance,  and  that  such  phenom- 
ena as  are  involved  in  telephonic  induction  be- 
tween circuits  could  have  no  other  meaning 
than  the  one  assigned  by  Maxwell,  yet  nearly 
all  the  physicists  failed  to  form  the  only  con- 
ception of  it  that  was  possible,  and  waited  for 
Hertz  to  devise  apparatus  for  producing  inter- 
ference before  they  grasped  it.  It  was  even 
then  so  new  to  some,  that  it  was  proclaimed  to 
be  a  demonstration  of  the  existence  of  the 
ether  itself,  as  well  as  a  method  of  producing 
waves  short  enough  to  enable  one  to  notice  in- 
terference phenomena.  It  is  obvious  that  Hertz 
himself  must  have  had  the  mechanics  of  wave 
motion  plainly  in  mind,  or  he  would  not  have 
planned  such  experiments.  The  outcome  of  it 
all  is,  that  we  now  have  experimental  proof,  as 
well  as  theoretical  reason,  for  believing  that  the 
ether,  once  called  luminiferous,  is  concerned  in 
all  electric  and  magnetic  phenomena,  and  that 
waves  set  up  in  it  by  electro-magnetic  actions 


1 8  MODES  OF  MOTION 

are  capable  of  being  reflected,  refracted,  polar- 
ized, and  twisted,  the  same  as  ordinary  light- 
waves can  be,  and  that  the  laws  are  applicable 
to  both. 


DISCONTINUITY  1 9 


CHAPTER    II 

PROPERTIES  OF  MATTER  AND  ETHER 

A  COMMON  conception  of  the  ether  has  been, 
that  it  is  a  finer-grained  substance  than  ordinary 
matter,  but  otherwise  so  like  the  latter  that  the 
laws  found  to  hold  good  with  matter  were  as 
applicable  to  the  ether ;  and  hence  the  mechan- 
ical conceptions  formed  from  experience  with 
the  one  have  been  transferred  to  the  other,  and 
the  properties  belonging  to  one,  such  as  den- 
sity, elasticity,  etc.,  have  been  asserted  as  prop- 
erties of  the  other. 

There  is  so  considerable  a  body  of  knowledge 
bearing  upon  the  similarities  and  dissimilarities 
of  these  two  entities,  that  it  will  be  well  to  com- 
pare them.  One  may  then  be  better  able  to 
judge  of  the  propriety  of  assuming  them  to  be 
subject  to  identical  laws. 

1.     MATTER   IS   DISCONTINUOUS. 

It  is  made  up  of  atoms  having  dimensions 
which  have  been  approximately  determined  to 


2O  MODES  OF  MOTION 

be  in  the  neighborhood  of  the  one  fifty  mil- 
lionth of  an  inch  in  diameter.  These  may  have 
various  degrees  of  aggregation,  —  practical  con- 
tact, as  in  most  solid  bodies,  like  the  metals  and 
rocks  ;-in  molecular  groupings,  as  in  water  and 
gases  such  as  hydrogen,  oxygen,  and  so  forth, 
where  two,  three,  or  more  atoms  cohere  so 
strongly  as  to  enable  the  molecules  to  act  un- 
der ordinary  circumstances  like  simple  particles. 
Any  or  all  of  these  molecules  and  atoms  may 
be  separated  by  any  assignable  distance  from 
each  other.  Thus,  in  common  air  the  mole- 
cules, though  rapidly  changing  their  positions, 
are  on  the  average  about  two  hundred  and  fifty 
times  their  own  diameter  apart.  This  is  a 
distance  relatively  greater  than  the  distance 
apart  of  the  earth  and  the  moon ;  for  two  hun- 
dred and  fifty  times  the  diameter  of  the  earth 
will  be  8,060x250=2,000,000  miles,  while  the 
distance  to  the  moon  is  but  240,000  miles.  The 
sun  is  93,000,000  miles  from  the  earth ;  and  the 
most  of  the  bodies  of  the  solar  system  are  still 
more  widely  separated,  Neptune  being  nearly 
3,000  millions  of  miles  from  the  sun.  As  for 
the  stars,  they  are  so  far  separated  from  us, 
that,  at  the  present  rate  of  motion  in  its  drift 
through  space,  500  millions  of  miles  in  a  year, 
it  would  take  not  less  than  40,000  years  to  reach 
our  nearest  neighbor,  while  for  the  more  remote 


ETHER  IS  CONTINUOUS  21 

ones  millions  of  years  must  be  reckoned.  This 
huge  space  which  separates  these  masses  is 
practically  devoid  of  matter  ;  it  is  a  vacuum. 

THE    ETHER    IS    CONTINUOUS. 

The  idea  of  continuity  as  distinguished  from 
discontinuity  may  be  gained  by  considering 
what  would  be  visible  by  magnification.  Water 
appears  to  the  eye  as  if  it  were  without  pores ; 
but  if  sugar  or  salt  be  put  into  it,  either  will  be 
dissolved,  and  quite  disappear  among  the  mole- 
cules of  the  water,  as  steam  does  in  the  air, 
which  shows  that  there  are  some  unoccupied 
spaces  between  the  molecules.  If  a  microscope 
be  employed  to  magnify  a  minute  drop  of  water, 
it  still  shows  the  same  lack  of  structure  as  that 
looked  at  with  the  unaided  eye.  If  the  mag- 
nifying power  be  the  highest,  it  may  reveal  a 
speck  as  small  as  the  hundred  thousandth  part 
of  an  inch,  yet  the  speck  looks  no  different  in 
character.  We  know  that  water  is  composed  of 
two  different  kinds  of  atoms,  hydrogen  and  oxy- 
gen ;  for  they  can  be  separated  by  chemical 
means,  and  kept  in  separate  bottles,  and  again 
made  to  combine  to  form  water,  having  all  the 
qualities  that  belonged  to  it  before  it  was  de- 
composed. If  a  still  higher  magnifying  power 
were  available,  we  are  very  sure  we  should  ulti- 


22  MODES  OF  MOTION 

mately  be  able  to  see  the  individual  water  mole- 
cules, and  recognize  their  hydrogen  and  oxygen 
constituents  by  their  difference  in  size,  rate  of 
movements,  and  separate  them  by  mechanical 
methods.  What  one  would  see  would  be  some- 
thing very  different  in  structure  from  the  water 
as  it  appears  to  our  eyes.  If  the  ether  were 
similarly  to  be  examined  through  higher  and 
still  higher  magnifying  powers,  even  up  to  in- 
finity, there  is  no  reason  for  thinking  that  the 
last  examination  would  show  anything  different 
in  structure  or  quality  from  that  which  was  ex- 
amined with  low  power,  or  with  no  microscope 
at  all.  This  is  all  expressed  by  saying  that  the 
ether  is  a  continuous  substance,  without  inter- 
stices ;  that  it  fills  space  completely,  and,  unlike 
gases,  liquids,  and  solids,  is  incapable  of  absorb- 
ing or  dissolving  anything. 

2.     MATTER   IS   LIMITED. 

There  appears  to  be  a  definite  amount  of  it  in 
the  visible  universe,  a  definite  number  of  mole- 
cules and  atoms.  How  many  molecules  there 
are  in  a  cubic  inch  of  air,  under  ordinary  pres- 
sure, has  been  determined,  and  is  represented 
approximately  by  a  huge  number,  something 
like  a  thousand  million  million  millions. 

When  the  diameter  of  a  molecule  has  been 


MATTER   IS  LIMITED  2$ 

measured,  as  it  has  been  approximately,  and 
found  to  be  about  one  fifty  millionth  of  an  inch, 
then  fifty  million  in  a  row  would  reach  an  inch, 
and  the  cube  of  fifty  million  is 

1 2  5000,000000,000000,000000, 

one  hundred  and  twenty-five  thousand  million 
million  millions.  In  a  cubic  foot  there  will, 
of  course,  be  1,728  times  that  number.  One 
may,  if  he  likes,  find  how  many  there  may  be 
in  the  earth  and  moon,  sun  and  planets  ;  for 
the  dimensions  of  them  are  all  very  well  known. 
Only  the  multiplication  table  need  be  used,  and 
the  sum  of  all  these  will  give  how  many  mole- 
cules there  are  in  the  solar  system.  If  one 
should  feel  that  the  number  thus  obtained  was 
not  very  accurate,  he  might  reflect  that  if 
there  were  ten  times  as  many  it  would  add 
but  another  cipher  to  a  long  line  of  similar 
ones,  and  would  not  materially  modify  it.  The 
point  is,  that  there  is  a  definite,  computable 
number.  If  one  will  then  add  to  these  the 
number  of  molecules  in  the  more  distant  stars 
and  nebulae,  of  which  there  are  visible  about 
100,000000,  making  such  estimate  of  their  in- 
dividual size  as  he  thinks  prudent,  the  sum  of 
all  will  give  the  number  of  molecules  in  the  vis- 
ible universe.  The  number  is  not  so  large  but 
it  can  be  written  down  in  a  minute  or  two. 


24  MODES  OF  MOTION 

Those  who  have  been  to  the  pains  to  do  the 
sum,  say  it  may  be  represented  by  7,  followed 
by  ninety-one  ciphers.  One  could  easily  com- 
pute how  many  molecules  so  large  a  space  would 
contain  if  it  were  full,  and  as  closely  packed  as 
they  are  in  a  drop  of  water ;  but  there  would  be 
a  finite,  and  not  an  infinite,  number,  and  there- 
fore there  is  a  limited  number  of  atoms  in  the 
visible  universe. 

THE    ETHER    IS    UNLIMITED.     . 

The  evidence  for  this  comes  to  us  from  the 
phenomena  of  light.  Experimentally,  ether- 
waves  of  all  lengths  are  found  to  have  a  velo- 
city of  186,000  miles  in  a  second.  It  takes  about 
eight  minutes  to  reach  us  from  the  sun,  four 
hours  from  Neptune,  the  most  distant  planet, 
and  from  the  nearest  fixed  stars  about  three 
and  a  half  years.  Astronomers  tell  us  that 
some  visible  stars  are  so  distant  that  their  light 
requires  not  less  than  ten  thousand  years,  and 
probably  more,  to  reach  us,  though  travelling  at 
the  enormous  rate  of  186,000  miles  a  second. 
This  means  that  the  whole  of  the  space  is  filled 
with  this  medium.  If  there  were  any  vacant 
spaces,  the  light  would  fail  to  get  through  them, 
and  stars  beyond  them  would  become  invisible. 
There  are  no  such  vacant  spaces  ;  for  any  part 
of  the  heavens  shows  stars  beaming  continu- 


ETHER    UNLIMITED  2$ 

ously,  and  every  increase  in  telescopic  power 
shows  stars  s.till  farther  removed  than  any  seen 
before.  The  whole  of  this  intervening  space 
must,  therefore,  be  filled  with  the  ether.  Some 
of  the  waves  that  reach  us  are  not  more  than 
the  hundred  thousandth  of  an  inch  long  ;  so 
there  can  be  no  crack  or  break  or  absence  of 
ether  from  so  small  a  section  as  the  hundred 
thousandth  of  an  inch  in  all  this  great  expanse. 
More  than  this.  No  one  can  think  that  the 
remotest  visible  stars  are  upon  the  boundary  of 
space ;  that  if  one  could  get  to  the  most  distant 
star,  he  could  have  on  one  side  the  whole  of 
space,  while  the  opposite  side  was  devoid  of  it. 
The  space  we  know  is  of  three  dimensions ;  and 
a  straight  line  may  be  prolonged  in  any  direc- 
tion to  an  infinite  distance,  and  a  ray  of  light 
may  travel  on  for  an  infinite  time,  and  come  to 
no  end,  provided  the  space  be  filled  with  ether. 
How  long  the  sun  and  stars  have  been  shin- 
ing no  one  knows ;  but  it  is  highly  probable 
that  the  sun  has  existed  for  not  less  than  1,000 
million  years,  and  has  during  that  time  been 
pouring  its  rays  as  radiant  energy  into  space. 
If,  then,  in  half  that  time,  or  500  millions  of 
years,  the  light  had  somewhere  reached  a  boun- 
dary to  the  ether,  it  could  not  have  gone  be- 
yond, but  would  have  been  reflected  back  into 
the  ether-filled  space,  and  such  part  of  the  sky 


26  MODES  OF  MOTION 

would  be  light  from  this  reflected  light.  There 
is  no  indication  that  anything  like  reflection 
comes  to  us  from  the  sky.  This  is  equivalent 
to  saying  that  the  ether  fills  space  in  every 
direction  from  us  to  an  unlimited  distance,  and 
so  far  is  itself  unlimited. 


3.     MATTER    IS   HETEROGENEOUS. 

The  various  kinds  of  matter  we  are  acquainted 
with  are  commonly  called  the  elements.  These 
when  combined  in  various  ways  exhibit  char- 
acteristic phenomena  which  depend  upon  the 
kinds  of  matter,  the  structure,  and  motions 
which  are  involved.  There  are  some  seventy 
different  kinds  of  this  elemental  matter  which 
may  be  identified  as  constituents  of  the  earth. 
Many  of  the  same  elements  have  been  identi- 
fied in  the  sun  and  stars ;  such,  for  instance,  as 
hydrogen,  carbon,  and  iron.  Such  phenomena 
lead  us  to  conclude  that  the  kinds  of  matter 
elsewhere  in  the  universe  are  identical  with 
such  as  we  are  familiar  with,  and  that  elsewhere 
the  variety  is  as  great.  The  qualities  of  the  ele- 
ments are  permanent;  they  are  not  subject  to 
fluctuations,  though  the  qualities  of  combina- 
tions of  them  may  vary  indefinitely.  The  ele- 
ments, therefore,  retain  their  identity  through 
all  kinds  of  changes. 


MATTER   IS  ATOMIC  2 7 

THE    ETHER    IS    HOMOGENEOUS. 

One  part  is  precisely  like  any  other  part 
everywhere  and  always,  and  there  are  no  such 
distinctions  in  it  as  correspond  with  the  ele- 
mental forms  of  matter. 


4.     MATTER   IS    ATOMIC. 

That  is,  there  is  -an  ultimate  particle  of  each 
one  of  the  elements  which  is  practically  abso- 
lute. The  atom  retains  its  identity  through  all 
combinations  and  processes.  It  may  be  here 
or  there,  move  fast  or-  slow,  its  atomic  form 
persists. 

THE    ETHER    IS    NON-ATOMIC. 

One  might  infer  from  what  has  already  been 
said  about  continuity,  that  the  ether  could  not 
be  constituted  of  separable  particles  like  masses 
of  matter  ;  for  no  matter  how  minute  they  might 
be,  there  would  be  interspaces  and  unoccupied 
spaces  which  would  present  us  with  phenomena 
which  have  never  been  seen.  It  is  the  general 
consensus  of  opinion  among  those  who  have 
studied  the  subject,  that  the  ether  is  not  atomic 
in  structure. 


28  MODES   OF  MOTION 


5.     MATTER   HAS   DEFINITE    STRUCTURE. 

Every  atom  of  every  element  is  so  like  every 
other  atom  of  the  same  element  as  to  show 
the  same  characteristics, — size,  weight,  chem- 


Fig.  4, 

To  make  vortex  rings  (Fig.  4),  provide  a  box  with  a  hole  in  front  and  a  flex- 
ible back  of  cloth.  Saucers  containing  ammonia  and  hydrochloric  acid 
will  fill  the  box  with  dense  white  fumes.  A  stroke  on  the  back  of  the 
box  will  expel  a  vortex  ring. 


ical  activity,  vibratory  rate,  etc.,  —  and  thus 
shows  conclusively  that  the  structural  form  of 
the  elemental  particles  is  the  same  for  each 
element ;  for  such  characteristic  reactions  as 


VORTEX  RIArGS  29 

they  exhibit  could  hardly  be  if  they  were  me- 
chanically unlike. 

Just  what  form  the  atoms  of  an  element  may 
be  is  not  very  definitely  known.  The  earlier 
philosophers  assumed  them  to  be  hard,  round 
particles ;  but  later  ones  have  concluded  that 
such  atoms  are  highly  improbable,  for  they 
could  not  exhibit  such  properties  as  the  ele- 
ments do  exhibit.  They  have,  therefore,  dis- 
missed such  a  conception  from  consideration. 
In  its  place  has  been  substituted  a  very  differ- 
ent idea ;  namely,  that  an  atom  is  a  vortex  ring 
of  ether  floating  in  the  ether,  as  a  smoke  ring 
puffed  out  by  a  locomotive  in  still  air  may  float 
in  the  air,  and  show  various  phenomena. 

A  vortex  ring  produced  in  the  air  (Fig.  4) 
behaves  in  the  most  surprising  manner. 

1.  It  retains  its  ring  form  and  the  same  ma- 

terial rotating  as  it  starts  with. 

2.  It  can  travel  through  the  air  easily  twenty 

or  thirty  feet  in  a  second  without  dis- 
ruption. 

3.  Its  line  of  motion  when  free  is  always  at 

right  angles  to  the  plane  of  the  ring. 

4.  It  will  not  stand  still  unless  compelled  by 

some  object.  If  stopped  in  the  air,  it 
will  start  up  itself  to  travel  on  without 
external  help. 


30  MODES  OF  MOTION 

5.  It  possesses  momentum  and  energy  like  a 

solid  body. 

6.  It  is  capable  of  vibrating  like  an  elastic 

body,  making  a  definite  number  of  such 
vibrations  per  second,  —  the  degree  of 
elasticity  depending  upon  the  rate  of 
vibration.  The  swifter  the  rotation, 
the  more  rigid  and  elastic  it  is. 

7.  It  is  capable  of  spinning  on  its  own  axis, 

and  thus  having  rotary  energy  as  well 
as  translatory  and  vibratory. 

8.  It  repels  light  bodies  in  front  of  it,  and  at- 

tracts into  itself  light  bodies  in  its  rear. 

9.  If  projected  along  parallel  with  the  top  of 

a  long  table,  it  will  fall  upon  it  every 
time,  as  a  stone  thrown  horizontally  will 
fall  to  the  ground. 

10.  If  two  rings  of  the  same  size  be  travelling 

in  the  same  line,  and  the  rear  one  over- 
takes the  other,  the  front  one  will  en- 
large its  diameter,  while  the  rear  one 
will  contract  its  own  till  it  can  go 
through  the  forward  one,  when  each 
will  recover  its  original  diameter,  and 
continue  on  in  the  same  direction,  but 
vibrating,  expanding,  and  contracting 
its  diameter  with  regularity. 

11.  If  two  rings  be  moving  in  the  same  line, 


VORTEX  RINGS  31 

but  in  opposite  directions,  they  will  re- 
pel each  other  when  near,  and  thus  re- 
tard their  speed.  If  one  goes  through 
the  other,  as  in  the  former  case,  it  may 
quite  lose  its  velocity,  and  come  to  a 
standstill  in  the  air  till  the  other  has 
moved  on  to  a  distance,  when  it  will 
start  up  in  its  former  direction. 

12.  If  two  rings  be  formed  side  by  side,  they 

will  instantly  collide  at  their  edges, 
showing  strong  attraction. 

13.  If  the   collision    does   not  destroy  them, 

they  may  either  break  apart  at  the 
junction  of  the  collision,  and  then  weld 
together  into  a  single  ring,  with  twice 
the  diameter,  and  then  move  on  as  if 
a  single  ring  had  been  formed,  or  they 
may  simply  bound  away  from  each 
other  ;  in  which  case  they  always  re- 
bound in  a  plane  at  rigJit  angles  to  the 
plane  of  collision.  That  is,  if  they  col- 
lided on  their  sides  they  would  rebound 
so  that  one  went  up  and  the  other  down. 

14.  Three  may  in   like  manner  collide,  and 

fuse  into  a  single  ring. 

Such  rings  formed  in  air  by  a  locomotive 
may  rise  wriggling  in  the  air  to  the  height  of 
several  hundred  feet,  but  presently  they  are 


32  MODES  OF  MOTION 

dissolved  and  disappear.  This  is  because  the 
friction  and  viscosity  of  the  air  robs  the  rings 
of  their  substance  and  energy.  If  the  air  were 
without  friction  this  could  not  happen  ;  and  the 
rings  would  then  be  persistent,  and  would  re- 
tain all  their  qualities. 

Suppose,  then,  that  such  rings  were  produced 
in  a  medium  without  friction,  as  the  ether  is 
believed  to  be;  they  would  be  permanent  struc- 
tures with  a  variety  of  properties.  They  would 
occupy  space,  have  definite  form  and  dimen- 
sions, momentum,  energy,  attraction  and  repul- 
sion, elasticity,  obey  the  laws  of  motion,  and 
so  far  behave  quite  like  such  matter  as  we 
know.  For  such  reasons  it  is  thought  by  some 
persons  to  be  not  improbable  that  the  atoms  of 
matter  are  minute  vortex  rings  of  ether  in  the 
ether.  That  which  distinguishes  the  atom  from 
the  ether  is  the  form  of  motion  which  is  em- 
bodied in  it  ;  and  if  the  motion  simply  were 
arrested,  there  would  be  nothing  to  distinguish 
the  atom  that  was  from  the  ether  it  dissolved 
into.  In  other  words,  such  a  conception  makes 
the  atoms  of  matter  a  form  of  motion  of  the 
ether,  and  not  a  created  something  put  into  the 
ether. 

THE    ETHER    IS    STRUCTURELESS. 

If  the  ether  be  the  boundless  substance  de- 
scribed, it  is  clear  it  can  have  no  form  as  a 


MATTER   GRAVITATIVE  33 

whole  ;  and  if  it  be  continuous,  it  can  have  no 
minute  structure.  If  not  constituted  of  atoms 
or  molecules,  there  is  nothing  descriptive  that 
can  be  said  about  it.  A  molecule  or  a  particu- 
lar mass  of  matter  could  be  identified  by  its 
form,  and  thus  is  in  marked  contrast  with  any 
portion  of  ether,  for  it  could  not  be  identified  in 
a  similar  way.  One  may  therefore  say  that  the 
ether  is  formless. 


6.     MATTER   IS    GRAVITATIVE. 

The  law  of  gravitation  is  held  as  being  uni- 
versal. It  states  that  every  particle  of  matter 
in  the  universe  attracts  every  other  particle. 
The  evidence  for  it  in  the  solar  system  is  com- 
plete. Sun,  planets,  satellites,  comets,  and  me- 
teors are  all  controlled  by  it  in  a  gravitative 
way ;  and  the  movements  of  double  stars  testify 
to  its  activity  in  the  more  distant  bodies  of  the 
universe.  The  attraction  does  not  depend  upon 
the  kind  of  matter,  nor  the  arrangement  of 
molecules  or  atoms,  but  upon  the  amount  or 
mass  of  matter  present  ;  and  if  it  be  of  a  defi- 
nite kind  of  matter,  as  of  hydrogen  or  iron,  the 
gravitative  action  is  proportional  to  the  number 
of  atoms. 


34  MODES  OF  MOTION 

THE    ETHER    IS    GRAVITATIONLESS. 

One  might  infer  already  that  if  the  ether 
were  structureless,  physical  laws  operative  upon 
such  material  substances  as  atoms  could  not  be 
applicable  to  it ;  and  so,  indeed,  all  the  evidence 
we  have  shows  that  gravitation  is  not  one  of 
its  properties.  If  it  were,  and  it  behaved  in 
any  degree  like  atomic  structures,  it  would  be 
found  to  be  denser  in  the  neighborhood  of  large 
bodies  like  the  earth,  planets,  and  the  sun. 
Light  would  be  turned  from  its  straight  path 
while  travelling  in  such  denser  medium,  or 
made  to  move  with  less  velocity.  There  is  not 
the  slightest  indication  of  any  such  effect  any- 
where within  the  range  of  astronomical  vision. 

Gravitation,  then,  is  a  property  belonging  to 
matter,  and  not  to  ether.  The  impropriety  of 
thinking  or  speaking  of  the  ether  as  matter 
of  any  kind  will  be  apparent  if  one  reflects 
upon  the  significance  of  the  law  of  gravitation 
as  stated.-  Every  particle  of  matter  in  the  uni- 
verse attracts  every  other  particle.  If  there  be 
anything  else  in  the  universe  which  has  no 
such  quality,  then  it  should  not  be  called  mat- 
ter, else  the  law  should  read :  Some  particles 
of  matter  attract  some  other  particles,  which 
would  be  no  law  at  all ;  for  a  real  physical  law 
has  no  exceptions  any  more  than  the  multipli- 


FRICTION  35 

cation  table  has.    Physical  laws  are  physical  re- 
lations, and  all  such  relations  are  quantitative. 


7.     MATTER  IS  FRICTIONABLE. 

A  bullet  shot  into  the  air  has  its  velocity  con- 
tinuously reduced  by  the  air  to  which  its  energy 
is  imparted  by  making  it  move  out  of  its  way. 
A  railway  train  is  brought  to  rest  by  the  fric- 
tion-brake upon  the  wheels.  The  translatory 
energy  of  the  train  is  transformed  into  the 
molecular  energy  called  heat.  The  steamship 
requires  to  propel  it  fast  a  large  amount  of 
coal  for  its  engines  ;  for  the  water  offers  great 
friction  resistance,  which  must  be  overcome. 
Whenever  one  surface  of  matter  is  moved  in 
contact  with  another  surface,  there  is  a  resist- 
ance called  friction,  the  moving  body  loses  its 
rate  of  motion,  and  will  presently  be  brought 
to  rest  unless  energy  be  continuously  supplied. 
This  is  true  for  masses  of  matter  of  all  sizes, 
and  with  all  kinds  of  motion.  Friction  is  the 
condition  for  the  transformation  of  all  kinds  of 
mechanical  motions  into  heat.  The  test  for  the 
amount  of  friction  is  the  rate  of  loss  of  motion. 
A  top  will  spin  some  time  in  the  air,  because 
its  point  is  small.  It  will  spin  longer  on  a 
plate  than  on  the  carpet,  and  longer  in  a  vac- 


36  MODES   OF  MOTION 

uum  than  in  the  air ;  for  it  does  not  have  the  air 
friction  to  resist  it,  and  there  is  no  kind  or  form 
of  matter  not  subject  to  frictional  resistance. 


THE    ETHER    IS    FRICTIONLESS. 

The  earth  is  a  mass  of  matter  moving  in  the 
ether.  In  the  equatorial  region  the  velocity 
of  a  point  is  more  than  a  thousand  miles  in 
an  hour ;  for  the  circumference  of  the  earth  is 
twenty-five  thousand  miles,  and  it  turns  once 
on  its  axis  in  twenty-four  hours,  which  is  the 
length  of  the  day.  If  the  earth  were  thus  spin- 
ning in  the  atmosphere,  the  latter  not  being  in 
motion,  the  wind  would  blow  with  ten  times 
hurricane  velocity.  The  friction  would  be  so 
great  that  nothing  but  the  foundation  rocks  of 
the  earth's  crust  could  withstand  it,  and  the  ve- 
locity of  rotation  would  be  reduced  appreciably 
in  a  relatively  short  time.  The  air  moves  along 
with  the  earth  as  a  part  of  it,  and  consequently 
no  such  frictional  destruction  takes  place;  but 
the  earth  rotates  in  the  ether  with  that  same 
rate,  and  if  the  ether  offered  resistance  it  would 
react  so  as  to  retard  the  rotation  and  increase 
the  length  of  the  day.  Astronomical  observa- 
tions show  that  the  length  of  the  day  has  cer- 
tainly not  changed  so  much  as  the  tenth  of  a 
second  during  the  past  two  thousand  years. 


ETHER   FRICTIONLESS  37 

The  earth  also  revolves  about  the  sun,  having 
a  speed  of  about  nineteen  miles  in  a  second,  or 
sixty-eight  thousand  miles  an  hour.  This  mo- 
tion of  the  earth  and  the  other  planets  about 
the  sun  is  one  of  the  most  stable  phenomena  we 
know.  The  mean  distance  and  period  of  revo- 
lution of  every  planet  is  unalterable  in  the  long 
run.  If  the  earth  had  been  retarded  by  its  fric- 
tion in  the  ether,  the  length  of  the  year  would 
have  been  changed,  and  astronomers  would  have 
discovered  it.  They  assert  that  a  change  in  the 
length  of  a  year  by  so  much  as  the  hundredth 
of  a  second  has  not  happened  during  the  past 
thousand  years.  This,  then,  is  testimony  that  a 
velocity  of  nineteen  miles  a  second  for  a  thou- 
sand years  has  produced  no  effect  upon  the 
earth's  motion  that  is  noticeable.  Nineteen 
miles  a  second  is  not  a  very  swift  astronomical 
motion  ;  for  comets  have  been  known  to  have  a 
velocity  of  four  hundred  miles  a  second  when  in 
the  neighborhood  of  the  sun,  and  yet  they  have 
not  seemed  to  suffer  any  retardation,  for  their 
orbits  have  not  been  shortened.  Some  years  ago 
a  comet  was  noticed  to  have  its  periodic  time 
shortened  an  hour  or  two ;  and  the  explanation 
offered  at  first  was  that  the  shortening  was  due 
to  friction  in  the  ether,  although  no  other  comet 
was  thus  affected.  The  idea  was  soon  aban- 
doned, and  to-day  there  is  no  astronomical  evi- 


135952 


38  MODES  OF  MOTION 

dence  that  bodies  having  translatory  motion  in 
the  ether  meet  with  any  frictional  resistance 
whatever.  If  a  stone  could  be  thrown  in  inter- 
stellar space  with  a  velocity  of  fifty  feet  a  sec- 
ond, it  would  continue  to  move  in  a  straight  line 
with  the  same  speed  for  any  assignable  time. 

As  has  been  said,  light  moves  with  the  ve- 
locity of  186,000  miles  per  second,  and  it  may 
pursue  its  course  for  tens  of  thousands  of  years. 
There  is  no  evidence  that  it  ever  loses  either 
its  wave  length  or  energy.  It  is  not  trans- 
formed as  friction  would  transform  it,  else  there 
would  be  some  distance  at  which  light  of  given 
wave  length  and  amplitude  would  be  quite  ex- 
tinguished. The  light  from  distant  stars  would 
be  different  in  character  from  that  coming  from 
nearer  stars.  Furthermore,  as  the  whole  solar 
system  is  drifting  in  space  some  500  millions 
of  miles  in  a  year,  new  stars  would  be  coming 
into  view  in  that  direction,  and  faint  stars  would 
be  dropping  out  of  sight  in  the  opposite  di- 
rection, —  a  phenomenon  which  has  not  been 
observed.  Altogether,  the  testimony  seems  con- 
clusive that  the  ether  is  a  frictionless  medium, 
and  does  not  transform  mechanical  motion  into 
heat. 


DIFFERENTIATED   PROPERTIES  39 

8.     MATTER   IS    JEOLOTROPIC. 

That  is,  its  properties  are  not  alike  in  all  di- 
rections. Chemical  phenomena,  crystallization, 
magnetic  and  electrical  phenomena  show,  each 
in  their  way,  that  the  properties  of  atoms  are 
not  alike  on  opposite  faces.  Atoms  combine  to 
form  molecules ;  and  molecules  arrange  them- 
selves in  certain  definite  geometric  forms,  such 
as  cubes,  tetrahedra,  hexagonal  prisms,  and 
stellate  forms  with  properties  emphasized  on 
certain  faces  or  ends.  Thus  quartz  will  twist 
a  ray  of  light  in  one  direction  or  the  other,  de- 
pending upon  the  arrangement,  which  may  be 
known  by  the  external  form  of  the  crystal. 
Calc-spar  will  break  up  a  ray  of  light  into  two 
parts  if  the  light  be  sent  through  it  in  certain 
directions,  but  not  if  in  another.  Tourmaline 
polarizes  light  sent  through  its  sides,  and  be- 
comes positively  electrified  at  one  end  while 
being  heated.  Some  substances  will  conduct 
sound  or  light  or  heat  or  electricity  better  in 
one  direction  than  in  another.  All  matter  is 
magnetic  in  some  degree,  and  that  implies  po- 
larity. If  one  will  recall  the  structure  of  a 
vortex  ring,  he  will  see  how  all  the  motion  is 
inward  on  one  side,  and  outward  on  the  other, 
which  gives  different  properties  to  the  two 
sides,  —  a  push  away  from  it  on  one,  and  a  pull 
toward  it  on  the  other. 


40  MOD£S  OF  MOTION 

THE    ETHER    IS    ISOTROPIC. 

That  is,  its  properties  are  alike  in  every  di- 
rection. There  is  no  distinction  due  to  posi- 
tion. A  mass  of  matter  will  move  as  freely  in 
one  direction  as  in  another  ;  a  ray  of  light  of 
any  wave  length  will  travel  in  it  in  one  direc- 
tion as  freely  as  in  any  other ;  neither  velocity 
nor  direction  is  changed  by  the  action  of  the 
ether  alone. 

9.     MATTER   IS    CHEMICALLY    SELECTIVE. 

When  the  elements  combine  to  form  mole- 
cules, they  always  combine  in  definite  ways  and 
in  definite  proportions.  Carbon  will  combine 
with  hydrogen,  but  will  drop  it  if  it  can  get  oxy- 
gen. Oxygen  will  combine  with  iron  or  lead  or 
sodium,  but  cannot  be  made  to  combine  with 
fluorin.  No  more  than  two  atoms  of  oxygen 
can  be  made  to  unite  with  one  carbon  atom, 
nor  more  than  one  hydrogen  with  one  chlorin 
atom.  There  is  thus  an  apparent  choice  for 
the  kind  and  number  of  associates  in  molecular 
structure;  and  the  stability  of  a  molecule  de- 
pends altogether  upon  the  presence  in  its  neigh- 
borhood of  other  atoms  for  which  some  of  the 
elements  in  the  molecule  have  a  stronger  attrac- 
tion or  affinity  than  they  have  for  the  atoms 


CHEMICAL   PROPERTIES  4! 

they  are  now  combined  with.  Thus  iron  is  not 
stable  in  the  presence  of  water  molecules,  and 
it  becomes  iron  oxid  ;  iron  oxid  is  not  stable  in 
the  presence  of  hot  sulphur,  and  it  becomes  an 
iron  sulphid.  All  the  elements  are  thus  selec- 
tive ;  and  it  is  by  such  means  that  they  may  be 
chemically  identified. 

There  is  no  phenomenon  in  the  ether  that  is 
comparable  with  this.  Evidently  there  cannot 
be  unless  there  are  atomic  structures  having 
different  characteristics  in  some  degree  which 
the  ether  is  without. 


10.     THE  ELEMENTS  OF   MATTER  ARE  HARMONI- 
CALLY RELATED. 

It  is  possible  to  arrange  the  elements  in  the 
order  of  their  atomic  weights  in  columns  which 
will  show  communities  of  property.  Newlands, 
Mendelleef,  Meyer,  and  others  have  done  this. 
The  explanation  for  such  an  arrangement  has 
not  yet  been  forthcoming,  but  that  it  expresses 
a  real  fact  is  certain  ;  for  in  the  scheme  there 
are  several  gaps  representing  undiscovered  ele- 
ments, the  properties  of  which  could  be  pre- 
dicted by  their  associates  in  the  table.  Some 
of  these  have  since  been  discovered,  and  their 
atomic  weight  and  physical  properties  accord 
with  those  predicted. 


42  MODES  OF  MOTION 

With  the  ether  such  a  scheme  is  quite  impos- 
sible, for  the  reason,  evident  enough,  that  there 
are  no  different  things  to  relate.  Every  part  is 
just  like  every  other  part.  Where  there  are  no 
differences  and  no  distinctions,  there  can  be  no 
relations.  The  ether  is  quite  without  harmonic 
relations. 

11.     MATTER   EMBODIES   ENERGY. 

So  long  as  the  atoms  of  matter  were  regarded 
as  hard,  round  particles,  they  were  assumed  to 
be  inert,  and  only  active  when  acted  upon  by 
what  were  called  forces,  which  were  held  to  be 
entities  of  some  sort  independent  of  matter. 
These  could  pull  or  push  it  here  or  there,  but 
the  matter  was  itself  incapable  of  independent 
activity.  All  this  is  now  changed ;  and  we  are 
called  upon  to  consider  every  atom  as  being  it- 
self a  form  of  energy  in  the  same  sense  as  heat 
and  light  are  forms  of  energy,  the  energy  being 
embodied  in  particular  forms  of  motion.  Light, 
a  wave  motion  of  the  ether.  An  atom,  a  rotary 
ring  of  ether.  Stop  the  wave  motion,  and  the 
light  would  be  annihilated.  Stop  the  rotation, 
and  the  atom  would  be  annihilated  for  the  same 
reason.  As  the  ray  of  light  is  a  particular  em- 
bodiment of  energy,  and  has  no  existence  apart 
from  it,  so  an  atom  is  to  be  regarded  as  an  cm- 


MATTER  NOT  INERT  43 

bodimcnt  of  energy.  On  a  previous  page  it  is 
said  that  energy  is  the  ability  of  one  body  to 
act  upon  and  move  another  in  some  degree. 
An  atom  of  any  kind  is  not  the  inert  thing  it 
has  been  supposed  to  be,  for  it  can  do  some- 
thing. Even  at  absolute  zero,  when  all  its  vi- 
bratory or  heat  energy  is  absent,  it  is  still  an 
elastic,  whirling  body,  pulling  upon  every  other 
atom  in  the  universe  with  gravitational  energy, 
twisting  other  atoms  into  conformity  with  its 
own  position  with  its  magnetic  energy  ;  and 
if  an  ether  ring  acts  like  the  rings  which  are 
made  in  air,  it  will  not  stand  still  in  one  place, 
even  if  no  others  act  upon  it,  but  will  start  at 
once,  by  its  own  inherent  energy,  to  move  in 
a  right  line  at  right  angles  to  its  own  plane,  and 
in  the  direction  of  the  whirl  inside  trie  ring. 
Two  rings  of  wood  or  iron  might  remain  in 
contact  with  each  other  for  an  indefinite  time  ; 
but  vortex  rings  will  not,  but  will  beat  each 
other  away  as  two  spinning  tops  will  do  if  they 
touch  ever  so  gently.  If  they  do  not  thus  sep- 
arate, it  is  because  there  are  other  forms  of 
energy  acting  to  press  them  together ;  but  such 
external  pressure  will  be  lessened  by  the  ring's 
own  reactions. 

It  is  true  that  in  a  frictionless  medium  like 
the  ether,  one  cannot  at  present  see  how  such 
vortex  rings  could  be  produced  in  it.  Certainly 


44  MODES  OF  MOTION 

not  by  any  such  mechanical  methods  as  are 
employed  to  make  smoke  rings  in  air;  for  the 
friction  of  the  air  is  the  condition  for  produ- 
cing them.  However  they  came  to  be,  there  is 
implied  the  previous  existence  of  the  ether,  and 
of  energy  in  some  form  capable  of  acting  upon 
it  in  a  manner  radically  different  from  any 
known  in  physical  science. 

There  is  good  spectroscopic  evidence  that  in 
some  way  elements  of  different  kinds  are  now 
being  formed  in  nebulae  ;  for  the  simplest  show 
the  presence  of  hydrogen  alone.  As  they  in- 
crease in  complexity,  other  elements  are  added, 
until  the  spectrum  shows  most  of  the  elements 
we  know  of.  It  has  thus  seemed  likely,  either 
that  most  of  those  called  elements  are  composed 
of  molecular  groupings  of  some  fundamental  ele- 
ment which  by  proper  physical  methods  might 
be  decomposed,  as  one  can  now  decompose  a 
molecule  of  ammonia  or  sulphuric  acid,  or  that 
the  elements  are  now  being  created  by  some 
extra  physical  process  in  those  far-off  regions. 
In  either  case  an  atom  is  the  embodiment  of 
energy  in  such  a  form  as  to  be  permanent  un- 
der ordinary  physical  circumstances,  but  which 
if  in  any  manner  it  should  be  destroyed,  only 
the  form  would  be  lost.  The  ether  would  re- 
main, and  the  energy  which  was  embodied 
would  be  distributed  in  other  ways. 


ENERGY  BEHIND   ETHER  45 

THE    ETHER    IS    ENDOWED    WITH    ENERGY. 

The  distinction  between  energy  in  matter 
and  energy  in  the  ether  will  be  apparent  on 
considering  that  both  the  ether  and  energy  in 
some  form  must  be  conceived  as  existing  inde- 
pendent of  matter  ;  though  every  atom  were 
annihilated,  the  ether  would  remain,  and  all  the 
energy  embodied  in  the  atoms  would  be  still 
in  existence  in  the  ether.  The  atomic  energy 
would  simply  be  dissolved.  One  can  easily  con- 
ceive the  ether,  as  the  same  space-filling,  con- 
tinuous, unlimited  medium  without  an  atom  in 
it.  Assuming  that  it  is  clear  that  no  form  of 
energy  with  which  we  deal  in  physical  science 
would  have  any  existence  in  it ;  for  every  one 
of  those  forms,  gravitational,  thermal,  electric, 
magnetic,  or  any  other,  all  are  the  results  of 
the  forms  of  energy  in  matter.  If  there  were  no 
atoms,  there  would  be  no  gravitation  ;  for  that 
is  the  attraction  of  atoms  upoa  each  other.  If 
there  were  no  atoms,  there  could  be  no  atomic 
vibration,  therefore  no  heat,  and  so  on  for  each 
and  all;  nevertheless,  if  an  atom  be  the  embodi- 
ment of  energy,  there  must  have  been  energy 
in  the  ether  before  any  atom  existed.  One  of 
the  properties  of  the  ether  is  its  ability  to  dis- 
tribute energy  in  certain  ways,  but  there  is  no 
evidence  that  of  itself  it  ever  transforms  energy. 


46  MODES  OF  MOTION 

Once  a  given  kind  of  energy  in  it,  its  form 
does  not  change;  hence,  for  the  apparition  of  a 
form  of  energy  like  the  first  vortex  ring,  there 
must  have  been  not  only  energy,  but  some 
other  agency  capable  of  transforming  that  en- 
ergy into  a  permanent  structure.  To  the  best 
of  our  knowledge  to-day,  the  ether  would  be 
absolutely  helpless.  Such  energy  as  was  active 
in  forming  atoms  must  be  called  by  another 
name  than  what  is  appropriate  for  such  trans- 
formations as  occur  when,  for  instance,  me- 
chanical energy  of  a  bullet  is  transformed  into 
heat  when  the  target  is  struck.  Behind  the 
ether  must  be  assumed  some  agency  directing 
and  controlling  energy  in  a  manner  totally  dif- 
ferent from  any  operative  in  what  we  call  physi- 
cal science.  Nothing  short  of  what  is  called  a 
miracle  will  do,  —  an  event  without  a  physical 
antecedent  in  anyway  necessarily  related  to  its 
factors,  as  is  the  fact  of  a  stone  related  to  grav- 
ity, or  heat  to  an  electrical  current. 

Ether  energy  is  an  endowment  instead  of  be- 
ing an  embodiment,  and  implies  antecedents  of 
a  superphysical  kind. 

12.  MATTER  IS  AN  ENERGY  TRANSFORMER. 

As  each  different  kind  of  energy  represents 
some  specific  form  of  motion,  and  vice  versa, 


MATTER    TRANSFORMS  ENERGY  47 

» 

some  sort  of  mechanism  is  needful  for  trans- 
forming one  kind  into  another,  and  molecular 
structure  of  one  kind  or  another  is  essential. 
The  transformation  is  a  mechanical  process,  and 
matter  in  some  particular  and  appropriate  form 
is  an  essential  condition.  If  heat  appears,  then 
its  antecedent  has  been  some  other  form  of  mo- 
tion acting  upon  the  substance  heated.  It  may 
have  been  mechanical  motion  of  another  mass 
of  matter,  as  when  a  bullet  strikes  a  target  and 
becomes  heated  ;  or  it  may  be  friction,  as  when 
a  car-axle  heats  when  run  without  proper  oiling 
to  reduce  friction ;  or  it  may  be  condensation, 
as  when  tinder  is  ignited  by  condensing  the  air 
about  it ;  or  chemical  reactions  when  molecular 
structure  is  changed,  as  in  combustion ;  or  an 
electrical  current,  which  implies  a  dynamo  and 
steam-engine  or  water-power.  If  light  appears, 
its  antecedent  has  been  impact  or  friction,  con- 
densation or  chemical  action ;  and  if  electricity 
appears,  the  same  sort  of  antecedents  are  pres- 
ent. Whether  the  one  or  the  other  of  these 
forms  of  energy  is  developed  depends  upon  what 
kind  of  a  structure  the  antecedent  energy  has 
acted  upon.  If  radiant  energy,  so-called,  falls 
upon  a  mass  of  matter,  what  is  absorbed  is  at 
once  transformed  into  heat,  or  into  electric  or 
magnetic  effects :  which  one  of  these,  depends 
upon  the  character  of  the  mechanism  upon 


48  MODES  OF  MOTION 

which  the  radiant  energy  acts ;  but  the  radiant 
energy  itself,  which  consists  of  ether  waves,  is 
traceable  back,  in  every  case,  to  a  mass  of  mat- 
ter having  definite  characteristic  motions. 

One  may  therefore  say  with  certainty,  that 
every  physical  phenomenon  is  a  change  in  the 
direction  or  velocity  or  character  of  the  energy 
present ;  and  such  change  has  been  produced 
by  matter  acting  as  a  transformer. 

THE    ETHER    IS    A    NON-TRANSFORMER. 

It  has  already  been  said  that  the  absence 
of  friction  in  the  ether  enables  light-waves  to 
maintain  their  identity  for  an  indefinite  time, 
and  to  an  indefinitely  great  distance.  In  a  uni- 
form homogeneous  substance  of  any  kind,  any 
kind  of  energy  which  might  be  in  it  would  con- 
tinue in  it  without  any  change.  Uniformity 
and  homogeneity  imply  similarity  throughout, 
and  the  necessary  condition  for  transformation 
is  unlikeness.  One  might  not  look  for  any  kind 
of  a  physical  phenomenon  which  was  not  due 
to  the  presence  and  activity  of  some  heteroge- 
neity. 

As  a  ray  of  light  continues  a  ray  of  light  so 
long  as  it  exists  in  free  ether,  so  all  kinds  of 
radiations  of  whatever  wave  length  continue 
identical  until  they  fall  upon  some  mechanical 


ELASTICITY  49 

structure  called  matter.  Translatory  motion 
continues  translatory,  rotary  continues  rotary, 
and  vibratory  continues  to  be  vibratory ;  and  no 
transforming  change  can  take  place  in  the  ab- 
sence of  matter.  The  ether  is  helpless. 


13.     MATTER   IS    ELASTIC. 

It  is  commonly  stated  that  certain  substances, 
like  putty  and  dough,  are  inelastic ;  while  some 
other  substances,  like  glass,  steel,  and  wood,  are 
elastic.  This  quality  of  elasticity  as  manifested 
in  such  different  degrees  depends  upon  molec- 
ular combinations,  some  of  which,  as  in  glass 
and  steel,  are  favorable  for  exhibiting  it,  while 
others  mask  it;  for  the  ultimate  atoms  of  all 
kinds  are  certainly  highly  elastic. 

The  measure  of  elasticity  in  a  mass  of  matter 
is  the  velocity  with  which  a  wave  motion  will  be 
transmitted  through  it.  Thus,  the  elasticity  of 
the  air  determines  the  velocity  of  sound  in  it. 
If  the  air  be  heated,  the  elasticity  is  increased, 
and  the  sound  moves  faster.  The  rates  of  such 
sound-conduction  range  from  a  few  feet  in  a 
second  to  about  16,000,  five  times  swifter  than 
a  cannon-ball.  In  such  elastic  bodies  as  vibrate 
to  and  fro,  like  the  prongs  of  a  tuning-fork,  or 
give  sounds  of  a  definite  pitch,  the  rate  of  vi- 


50  MODES  OF  MOTION 

bration  is  determined  by  the  size  and  shape  of 
the  body,  as  well  as  by  their  elementary  compo- 
sition. The  smaller  a  body  is,  the  higher  its 
vibratory  rate,  if  it  be  made  of  the  same  mate- 
rial, and  the  form  remains  the  same.  Thus,  a 
tuning-fork  that  may  be  carried  in  the  vest 
pocket  may  vibrate  500  times  a  second.  If  it 
were  only  the  fifty  millionth  of  an  inch  in  size, 
but  of  the  same  material  and  form,  it  would  vi- 
brate 30000,000000  times  a  second ;  and  if  it 
were  made  of  ether  instead  of  steel,  it  would 
vibrate  as  many  times  faster  as  the  velocity  of 
waves  in  the  ether  is  greater  than  it  is  in  steel, 
and  would  be  as  many  as  400,000000,000000 
times  per  second.  The  amount  of  displace- 
ment, or  the  amplitude  of  vibration  with  the 
pocket  fork,  might  be  no  more  than  the  hun- 
dredth of  an  inch ;  and  this  rate  measured  as 
translation  velocity  would  be  but  five  inches 
per  second.  If  the  fork  were  of  atomic  magni- 
tude, and  should  swing  its  sides  one-half  the 
diameter  of  the  atom,  or,  say,  the  hundred  mil- 
lionth of  an  inch,  the  translational  velocity  would 
be  equivalent  to  about  eighty  miles  a  second,  or 
a  hundred  and  fifty  times  the  velocity  of  a  can- 
non-ball, which  may  be  reckoned  at  about  3,000 
feet  per  second. 

That  atoms  really  vibrate  at  the  above  rate 
per  second  is  very, certain  ;  for  their  vibrations 


ATOMIC    VIBRATIONS  51 

produce  ether-waves,  the  length  of  which  may 
be  accurately  measured.  When  a  tuning-fork 
vibrates  500  times  a  second,  and  the  sound 
travels  1,000  feet  in  the  same  interval,  the 
length  of  each  wave  will  be  found  by  dividing 
the  velocity  in  the  air  by  the  number  of  vibra- 
tions, or  1,100/500=2.2  feet.  In  like  manner, 
when  one  knows  the  velocity  and  wave  length 
he  may  compute  the  number  of  vibrations  by 
dividing  the  velocity  by  the  wave  length.  Now, 
the  velocity  of  the  waves  called  light  is  186,000 
miles  a  second,  and  a  light-wave  may  be  one 
forty  thousandth  of  an  inch  long.  The  atom 
that  produces  the  wave  must  be  vibrating  as 
many  times  per  second  as  the  forty  thousandth 
of  an  inch  is  contained  in  186,000  miles.  Re- 
ducing this  number  to  inches,  we  have  :  — 

186,000  X  c;,28o  X  12 

=  400,000000,000000  nearly. 

40,000 

This  shows  that  the  atoms  are  minute  elastic 
bodies  that  change  their  form  rapidly  when 
struck.  As  rapid  as  the  change  is,  yet  the  dis- 
tance moved  through  is  only  one-fifth  that  of  a 
comet  when  near  the  sun,  and  is  therefore  easily 
comparable  with  other  velocities  observed  in 
masses  of  matter. 

These  vibratory  motions  due  to  the  elasticity 
of  the  atoms  is  what  constitutes  heat. 


52  MODES  OF  MOTION 

THE    ETHER    IS    ELASTIC!! 

The  elasticity  of  a  mass  of  matter  is  its  abil- 
ity to  recover  its  original  form  after  that  form 
has  been  distorted.  There  is  implied  that  a 
stress  changes  its  shape  and  dimensions,  which 
in  turn  implies  a  limited  mass  and  relative 
change  of  position  of  parts  and  some  degree  of 
discontinuity.  From  what  has  been  said  of  the 
ether  as  being  unlimited,  continuous,  and  not 
made  of  atoms  or  molecules,  it  will  be  seen 
how  difficult,  if  not  impossible,  it  is  to  conceive 
how  such  a  property  as  elasticity  as  manifested 
in  matter  can  be  attributed  to  the  ether,  which 
is  incapable  of  deformation,  either  in  structure 
or  form,  the  latter  being  infinitely  extended  in 
every  direction,  and  therefore  formless.  Never- 
theless, certain  forms  of  motion,  such  as  light- 
waves, move  in  it  with  definite  velocity,  quite 
independent  of  how  they  originate.  This  ve- 
locity of  186,000  miles  a  second  so  much  ex- 
ceeds any  movement  of  a  mass  of  matter,  that 
they  can  hardly  be  compared.  Thus,  if  400 
miles  per  second  be  the  swiftest  speed  of  any 
mass  of  matter  known,  the  ether-wave  moves 
186,000  7400=465  times  faster  than  such  comet, 
and  900,000  times  faster  than  sound  travels  in 
air. 

It  is  clear  that  if  this  rate  of  motion  depends 


ELASTICITY  OF  ETHER  53 

upon  elasticity,  the  elasticity  must  be  of  an 
entirely  different  type  from  that  belonging  to 
matter,  and  cannot  be  denned  in  any  such  terms 
as  are  employed  for  matter. 

If  one  considers  gravitative  phenomena,  the 
difficulty  is  enormously  increased.  The  orbit  of 
a  planet  is  never  an  exact  ellipse,  on  account 
of  the  perturbations  produced  by' the  planetary 
attractions,  which  depend  upon  their  direction 
and  distance.  These,  however,  are  so  well 
known  that  slight  deviations  are  easily  noticed. 
If  gravitative  attraction  took  any  such  appre- 
ciable time  to  go  from  one  astronomical  body 
to  another  as  does  light,  it  would  make  very 
considerable  differences  in  the  paths  of  the 
planets  and  the  earth.  Indeed,  if  the  velocity 
of  gravitation  were  less  than  a  million  times 
greater  than  that  of  light,  its  effects  would 
have  been  discovered  long  ago.  It  is  there- 
fore considered  that  the  velocity  of  gravitation 
cannot  be  less  than  186000,000000  miles  per 
second.  How  much  greater  it  may  be  no  one 
can  guess.  Seeing  that  gravitation  is  ether 
pressure,  it  does  not  seem  probable  that  its 
velocity  can  be  infinite.  However  that  may 
be,  the  ability  of  the  ether  to  transmit  pressure 
and  various  disturbances  evidently  depends 
upon  properties  so  different  from  those  that 
enable  matter  to  transmit  disturbances,  that 


54 


MODES  OF  MOTION 


they  deserve  to  be  called  by  different  names. 
To  speak  of  the  elasticity  of  the  ether  may 
serve  to  express  the  fact  that  energy  may  be 
transmitted  at  a  finite  rate  in  it;  but  it  can 
only  mislead  one's  thinking  if  he  imagines  the 
process  to  be  similar  to  energy  transmission  in 
a  mass  of  matter.  The  two  processes  are  in- 
comparable. No  other  word  than  elasticity  has 
been  suggested,  and  perhaps  it  is  not  needful 
for  most  scientific  purposes  that  another  should 
"be  adopted;  but  the  inappropriateness  of  the 
one  word  for  the  different  phenomena  has  long 
been  felt. 

14.     MATTER  HAS  DENSITY. 

This  quality  is  exhibited  in  two  ways  in  mat- 
ter. In  the  first,  the  different  elements  in  their 
atomic  form  have  different  masses  or  atomic 
weights.  An  atom  of  oxygen  weighs  sixteen 
times  as  much  as  an  atom  of  hydrogen  ;  that  is, 
it  has  sixteen  times  as  much  matter  as  deter- 
mined by  weight  as  the  hydrogen  atom  has,  or 
it  takes  sixteen  times  as  many  hydrogen  atoms 
to  make  a  pound  as  it  takes  of  oxygen  atoms. 
This  is  generally  expressed  by  saying  that  oxy- 
gen has  sixteen  times  the  density  of  hydrogen. 
In  like  manner  iron  has  fifty-six  times  the 
density,  and  gold  one  hundred  and  ninety-six. 


DENSITY  5  5 

The  difference  is  one  in  the  structure  of  the 
atomic  elements.  If  one  imagines  them  to  be 
vortex  rings,  they  may  differ  in  size,  thickness, 
and  rate  of  rotation  ;  either  of  these  might 
make  all  the  observed  difference  between  the 
elements,  including  their  density.  In  the  sec- 
ond way,  density  implies  compactness  of  mole- 
cules. Thus  if  a  cubic  foot  of  air  be  compressed 
until  it  occupies  but  half  a  cubic  foot,  each 
cubic  inch  will  have  twice  as  many  molecules 
in  it  as  at  first.  The  amount  of  air  per  unit 
volume  will  have  been  doubled,  the  weight  will 
have  been  doubled,  the  amount  of  matter  as 
determined  by  its  weight  will  have  been  doubled ; 
and  consequently  we  say  its  density  has  been 
doubled. 

If  a  bullet  or  a  piece  of  iron  be  hammered, 
the  molecules  are  compacted  closer  together, 
and  a  greater  number  can  be  got  into  a  cubic 
inch  when  so  condensed.  In  this  sense,  then, 
density  means  the  number  of  molecules  in  a 
unit  of  space,  —  a  cubic  inch  or  cubic  centi- 
metre. There  is  implied  in  this  latter  case 
that  the  molecules  do  not  occupy  all  the  avail- 
able space ;  that  they  may  have  varying  degrees 
of  closeness  ;  in  other  words,  matter  is  discon- 
tinuous, and  therefore  there  may  be  degrees  in 
density. 


56  MODES   OF  MOTION 

THE    ETHER  .HAS    DENSITY  !  ! 

It  is  common  to  have  the  degree  of  density 
of  the  ether  spoken  of  in  the  same  way  and  for 
the  same  reason  that  its  elasticity  is  spoken  of. 
The  rate  of  transmission  of  a  physical  disturb- 
ance, as  of  a  pressure  or  a  wave  motion  in  mat- 
ter, is  conditioned  by  its  degree  of  density;  that 
is,  the  amount  of  matter  per  cubic  inch  as  de- 
termined by  its  weight :  the  greater  the  density 
the  slower  the  rate.  So  if  rate  of  speed  and 
elasticity  be  known,  the  density  may  be  com- 
puted. In  this  way  the  density  of  the  ether 
has  been  deduced  by  noting  the  velocity  of 
light.  The  enormous  velocity  is  supposed  to 
prove  that  its  density  is  very  small,  even  when 
compared  with  hydrogen.  This  is  stated  to  be 
about  equal  to  that  of  the  air  at  the  height  of 
two  hundred  and"  ten  miles  above  the  surface 
of  the  earth,  where  the  air  molecules  are  so  few 
that  a  molecule  might  travel  for  sixty  millions 
of  miles  without  coming  in  collision  with  an- 
other molecule.  In  air  of  ordinary  density  a 
molecule  can,  on  the  average,  move  no  farther 
than  about  the  two  hundred  and  fifty  thou- 
sandth of  an  inch  without  such  collision.  It  is 
plain  the  density  of  the  ether  is  so  far  removed 
from  the  density  of  anything  we  can  measure, 
that  it  is  hardly  comparable  with  such  things. 


HEAT  57 

If,  in  addition,  one  recalls  the  fact  that  the  ether 
is  homogeneous, — that  is,  all  of  one  kind, — and 
also  that  it  is  not  composed  of  atoms  and  mole- 
cules, then  degree. of  compactness  and  number 
of  particles  per  cubic  inch  have  no  meaning, 
and  the  term  density,  if  used,  can  have  no 
such  meaning  as  it  has  when  applied  to  matter. 
There  is  no  physical  conception  gained  from 
the  study  of  matter  that  can  be  useful  in  think- 
ing of  it.  As  with  elasticity,  so  density  is  in- 
appropriately applied  to  the  ether ;  but  there  is 
no  substitute  yet  offered.- 


15.     MATTER   IS    HEATABLE. 

So  long  as  heat  was  thought  to  be  some  kind 
of  an  imponderable  thing  which  might  retain 
its  identity  whether  it  were  in  or  out  of  matter, 
its  real  nature  was  obscured  by  the  name  given 
to  it.  An  imponderable  was  a  mysterious  some- 
thing, like  a  spirit,  which  was  the  cause  of 
certain  phenomena  in  matter.  Heat,  light, 
electricity,  magnetism,  gravitation,  were  due  to 
such  various  agencies,  that  no  one  concerned 
himself  with  the  nature  of  one  or  the  other. 
Bacon  thought  that  heat  was  a  brisk  agitation 
of  the  particles  of  substances,  and  Count  Rum- 
ford  and  Sir  Humphry  Davy  thought  they 


58  .  MODES  OF  MOTION 

proved  that  it  could  be  nothing  else  ;  but  they 
convinced  nobody.  Mayer  in  Germany,  and 
Joule  in  England,  showed  that  quantitative  re- 
lations existed  between  work  done  and  heat 
developed ;  but  not  until  the  publication  of  the 
book  called  Heat  as  a  Mode  of  Motion,  was  there 
a  change  of  opinion  and  terminology  as  to  the 
nature  of  heat.  For  twenty  years  after  that 
it  was  common  to' hear  the  expressions  "  heat  " 
and  "  radiant  heat,"  to  distinguish  between 
phenomena  in  matter  and  what  is  now  called 
radiant  energy  radiations,  or  simply  ether-waves. 
Not  until  the  necessity  for  distinguishing  be- 
tween different  forms  of  energy  and  the  con- 
ditions for  developing  them,  did  it  become  clear 
to  all  that  a  change  in  the  form  of  energy 
implied  a  change  in  the  form  of  motion  that 
embodied  it.  The  energy  called  heat  energy 
was  proved  to  be  a  vibratory  motion  of  mole- 
cules ;  and  what  happens  in  the  ether  as  a  re- 
sult of  such  vibrations  is  no  longer  spoken  of 
as  heat,  but  as  ether-waves.  When  it  is  re- 
membered that  the  ultimate  atoms  are  elastic 
bodies,  and  that  they  will,  if  free,  vibrate  in  a 
periodic  manner  when  struck  or  shaken  in  any 
way,  just  as  a  bell  will  vibrate  after  it  is  struck, 
it  is  easy  to  keep  in  mind  the  distinction  be- 
tween the  mechanical  form  of  motion  spent  in 
striking,  and  the  vibratory  form  of  the  motion 


HE A T  59 

produced  by  it.  The  latter  is  called  heat  ;  no 
other  form  of  motion  than  that  is  properly 
called  heat.  It  is  this  alone  that  represents 
temperature,  the  rate  and  amplitude  of  such 
atomic  and  molecular  vibrations  as  constitute 
change  of  form.  Where  molecules  like  those 
in  a  gas  have  some  freedom  of  movement 
between  impacts,  they  bound  away  from  each 
other  with  varying  velocities.  The  path  of 
such  motion  may  be  long  or  short,  depending 
upon  the  density  or  compactness  of  the  mole- 
cules ;  but  such  changes  in  position  are  not 
heat  for  a  molecule  any  more  than  the  flight  of 
a  musket-ball  is  heat,  though  it  may  be  trans- 
formed into  heat  on  striking  the  target. 

This  conception  of  heat  as  the  rapid  change 
in  form  of  atoms  and  molecules  due  to  their 
elasticity,  is  a  phenomenon  peculiar  to  matter. 
It  implies  a  body  possessing  form  that  may  be 
changed ;  elasticity,  that  its  changes  may  be  pe- 
riodic ;  and  degrees  of  freedom  that  secure  space 
for  the  changes.  Such  a  body  may  be  heated. 
Its  temperature  will  depend  upon  the  amplitude 
of  such  vibrations,  and  will  be  limited  by  the 
maximum  amplitude. 

THE    ETHER    IS    UNHEATABLE. 

The  translatory  motion  of  a  mass  of  matter, 
big  or  little,  through  the  ether,  is  not  arrested 


6O  MODES   OF  MOTION 

in  any  degree  so  far  as  observed ;  but  the  in- 
ternal vibratory  motion  sets  lip  waves  in  the 
ether,  the  ether  absorbs  the  energy,  and  the  am- 
plitude is  continually  lessened.  The  motion  has 
been  transferred  and  transformed  ;  transferred 
from  matter  to  the  ether,  and  transformed  from 
vibratory  to  waves  travelling  at  the  rate  of 
186,000  miles  per 'second.  The  latter  is  not 
heat,  but  the  result  of  heat.  With  the  ether 
constituted  as  described,  such  vibratory  motion 
as  constitutes  heat  is  impossible  to  it,  and  hence 
the  characteristic  of  heat  motion  in  it  is  im- 
possible ;  it  cannot,  therefore,  be  heated.  The 
space  between  the  earth  and  the  sun  may  have 
any  assignable  amount  of  energy  in  the  form  of 
ether-waves  or  light,  but  not  any  temperature. 
One  might  loosely  say  that  the  temperature  of 
empty  spaces  was  absolute  zero ;  but  that  would 
not  be  quite  correct,  for  the  idea  of  temperature 
cannot  properly  be  entertained  as  applicable  to 
the  ether.  To  say  that  its  temperature  was  ab- 
solute zero  would  serve  to  imply  that  it  might 
be  higher,  which  is  inadmissible. 

When  energy  has  been  transformed,  the  old 
name  by  which  the  energy  was  called  must  be 
dropped.  Ether  cannot  be  heated. 


INDES  TK  UC  TIBIL ITY  6 1 


16.     MATTER    IS    INDESTRUCTIBLE. 

This  is  commonly  said  to  be  one  of  the  es- 
sential properties  of  matter.  All  that  is  meant 
by  it,  however,  is  simply  this  :  In  no  physical 
or  chemical  process  to  which  it  has  been  exper- 
imentally subjected  has  there  been  any  appar- 
ent loss.  The  matter  experimented  upon  may 
change  from  a  solid  or  liquid  to  a  gas,  or  the 
molecular  change  called  chemical  may  result  in 
new  compounds,  but  the  weight  of  the  material 
and  its  atomic  constituents  have  not  appreciably 
changed.  That  matter  cannot  be  annihilated  is 
only  the  converse  of  the  proposition  that  matter 
cannot  be  created,  which  ought  always  to  be 
modified  by  adding,  "by  physical  or  chemical 
processes  at  present  known."  A  chemist  may 
work  with  a  few  grains  of  a  substance  in  a 
beaker  or  test-tube  or  crucible,  and  after  sev- 
eral solutions,  precipitations,  fusions,  and  dry- 
ings, may  find  by  final  weighing  that  he  has  not 
lost  any  appreciable  amount ;  but  how  much  is 
an  appreciable  amount  ?  A  fragment  of  matter 
the  ten  thousandth  of  an  inch  in  diameter  has 
too  small  a  weight  to  be  noted  in  any  balance, 
yet  it  would  be  made  up  of  thousands  of  mil- 
lions of  atoms.  Hence,  if  in  the  processes  to 
which  the  substance  has  been  subjected  there 
had  been  the  total  annihilation  of  thousands  of 


62  MODES  OF  MO  T JON 

millions  of  atoms,  such  phenomenon  would  not 
have  been  discovered  by  weighing.  Neither 
would  it  have  been  discovered  if  there  had  been 
a  similar  creation  or  development  of  new  mat- 
ter. All  that  can  be  asserted  concerning  such 
events  is  that  they  have  not  been  discovered 
with  our  means  of  observation. 

The  alchemists  sought  to  transform  one  ele- 
ment into  another,  as  lead  into  gold.  They  did 
not  succeed.  Presently  it  was  thought  to  be 
impossible,  and  the  attempt  to  do  it  an  absurd- 
ity. Lately,  however,  telescopic  observation  of 
what  is  going  on  in  nebulae,  which  has  already 
been  referred  to,  has  somewhat  modified  ideas 
of  what  is  possible  and  impossible  in  that  direc- 
tion. It  is  certainly  possible  roughly  to  con- 
ceive how  such  a  structure  as  a  vortex  ring  in 
the  ether  might  be  formed.  With  certain  po- 
larizing apparatus,  it  is  possible  to  produce  rays 
of  circularly  polarized  light.  These  are  rays  in 
which  the  motion  is  an  advancing  rotation,  like 
the  wire  in  a  spiral  spring.  If  such  a  line  of  ro- 
tations in  the  ether  were  flexible,  and  the  two 
ends  should  come  together,  there  is  reason  for 
thinking  they  would  weld  together,  in  which 
case  the  structure  would  become  a  vortex  ring, 
and  be  as  durable  as  any  other.  There  is  reason 
for  believing,  also,  that  somewhat  similar  move- 
ments are  always  present  in  a  magnetic  field; 


INDESTRUCTIBILITY  63 

and  though  we  do  not  know  how  to  make  them 
close  up  in  the  proper  way,  it  does  not  follow 
that  it  is  impossible  for  them  to  do  so. 

The  bearing  of  all  this  upon  the  problem  of 
transmutation  of  elements  is  evident.  No  one 
now  will  venture  to  deny  its  possibility  as 
strongly  as  it  was  denied  a  generation  ago.  It 
will  also  lead  one  to  believe  rather  gently  that 
matter  is  indestructible.  Assuming  the  vortex- 
ring  theory  of  atoms  to  be  true,  if  in  any  way 
such  a  ring  could  be  cut  or  broken,  there  would 
not  remain  two  or  more  fragments  of  a  ring  or 
atom.  The  whole  would  at  once  be  dissolved 
into  the  ether.  The  ring  and  rotary  energy 
that  constituted  it  an  atom  would  be  destroyed, 
but  not  the  substance  it  was  made  of,  nor  the 
energy  which  was  thus  embodied.  For  long 
times  the  philosophers  have  argued,  and  com- 
mon-sense has  agreed,  that  an  atom  which  could 
not  be  ideally  broken  into  two  parts  was  impos- 
sible, that  one  could  at  any  rate  think  of  half 
an  atom  as  a  real  objective  possibility.  This 
vortex-ring  theory  shows  easily  how  possible  it 
is  to-day  to  think  what  once  was  philosophically 
incredible.  It  shows  that  metaphysical  reason- 
ing may  be  never  so  clear  and  apparently  irref- 
ragable, yet  for  all  that  it  may  be  very  unsound. 
The  trouble  does  not  come  so  much  from  the 
logic  as  from  the  assumption  upon  which  the 


64  MODES  OF  MOTION 

logic  is  founded.  In  this  particular  case  the  as- 
sumption was,  that  the  ultimate  particles  of 
matter  were  hard,  irrefragable  somethings,  with- 
out necessary  relations  to  anything  else  or  to 
energy,  and  irrefragable  only  because  no  means 
had  been  found  of  breaking  them. 

The  destructibility  or  indestructibility  of  the 
ether  cannot  be  considered  from  the  same 
standpoint  as  that  for  matter,  either  ideally 
or  really.  Not  ideally,  because  we  are  utterly 
without  any  mechanical  conceptions  of  the  sub- 
stance upon  which  one  can  base  either  reason 
or -analogy  ;  and  not  really,  because  we  have  no 
experimental  evidence  as  to  its  nature  or  mode 
of  operation.  If  it  be  continuous,  there  are  no 
interspaces ;  and  if  it  be  illimitable,  there  is 
no  unfilled  space  anywhere.  Furthermore,  one 
might  infer  that  if  in  any  way  a  portion  of  the 
ether  could  be  annihilated,  what  was  left  would 
at  once  fill  up  the  vacated  space  so  there  would 
be  no  record  left  of  what  had  happened.  Ap- 
parently its  destruction  would  be  the  destruc- 
tion of  a  substance,  which  is  a  very  different 
thing  from  the  destruction  of  a  mode  of  mo- 
tion. In  the  latter,  only  the  form  of  the  motion 
need  be  changed  to  completely  obliterate  every 
trace  of  the  atom.  In  the  former,  there  would 
need  to  be  the  destruction  of  both  substance 
and  energy ;  for  it  is  certain,  for  reasons  yet  to 


INERTIA  65 

be  attended  to,  that  the  ether  is  saturated  with 
energy. 

One  may,  without  mechanical  difficulties, 
imagine  a  vortex  ring  destroyed.  It  is  quite 
different  with  the  ether  itself ;  for  if  it  were 
destroyed  in  the  same  sense  as  the  atom  of 
matter,  it  would  be  changed  into  something 
else  which  is  not  ether,  a  proposition  which 
assumes  the  existence  of  another  entity,  the  ex- 
istence for  which  is  needed  only  as  a  mechanical 
antecedent  for  the  ether.  The  same  assump- 
tion would  be  needed  for  this  entity  as  for  the 
ether;  namely,  something  out  of  which  it  was 
made,  and  this  process  of  assuming  antecedents 
would  be  interminable.  The  last  one  consid- 
ered would  have  the  same  difficulties  to  meet 
as  the  ether  has  now.  The  assumption  that  it 
was  in  some  way  and  at  some  time  created  is 
more  rational,  and  therefore  more  probable,  than 
that  it  either  created  itself,  or  that  it  always 
existed.  Considered  as  the  underlying  stratum 
of  matter,  it  is  clear  that  changes  of  any  kind 
in  matter  can  in  no  way  affect  the  quantity  of 
ether. 

17.      MATTER   IS    LNERTIATIVE. 

The  resistance  that  a  mass  of  matter  opposes 
to  a  change  in  its  position,  or.  rate  and  direction 


66  MODES  OF  MOTION 

of  movement,  is  called  inertia.  That  it  should  ac- 
tively oppose  anything  has  been  already  pointed 
out  as  reason  for  denying  that  matter  is  inert ; 
but  inertia  is  the  measure  of  the  reaction  of  a 
body  when  it  is  acted  upon  by  ^&fif&r°  from 
any  source  tending  to  disturb  its  condition  of 
either  rest  or  motion.  It  is  the  equivalent  of 
mass,  or  the  amount  of  matter  as  measured  by 
gravity,  and  is  a  fixed  quantity  for  the  atom, 
is  as  inherent  as  any  other  quality,  and  belongs 
to  the  ultimate  atoms  and  every  combination 
of  them.  It  implies  the  ability  to  absorb  en- 
ergy, for  it  requires  as  much  energy  to  bring  a 
moving  body  to  a  standstill  as  was  required  to 
give  it  its  forward  motion. 

Both  rotary  and  vibratory  movements  are  op- 
posed by  the  same  property.  A  grindstone,  a 
tuning-fork,  and  an  atom  of  hydrogen  require, 
to  move  them  in  their  appropriate  ways,  an 
amount  of  energy  proportionate  to  their  mass 
or  inertia,  which  energy  is  again  transformed, 
through  friction,  into  heat,  and  radiated  away. 

One  may  say  that  inertia  is  the  measure  of 
the  ability  of  a  body  to  transfer  or  transform 
mechanical  energy.  The  meteorite  that  falls 
upon  the  earth  to-day  gives,  on  its  impact,  the 
same  amount  of  energy  it  would  have  given  if 
it  had  struck  the  earth  ten  thousand  years  ago. 
The  inertia  of  the  meteor  has  persisted,  not  as 


INERTIA  67 

energy,  but  as  a  factor  of  energy.  We  com- 
monly express  the  energy  of  a  mass  of  matter 
by  mv*l2,  where  m  stands  for  the  mass  and  v 
for  its  velocity.  We  might  as  well,  if  it  were 
as  convenient,  substitute  inertia  for  mass,  and 
write  the  expression  iv2/2  ;  for  the  mass,  being 
measured  by  its  inertia,  is  only  the  more  com- 
mon and  less  definitive  word-for  the  same  thing. 
The  energy  of  a  mass  of  matter  is,  then,  propor- 
tional to  its  inertia,  because  inertia  is  one  of  its 
factors.  Energy  has  often  been  treated  as  if  it 
were  an  objective  thing,  an  entity  and  a  unity  : 
but  such  a  conception  is  evidently  wrong ;  for, 
as  has  been  said  before,  it  is  a  product  of  two 
factors,  either  of  which  may  be  changed  in  any 
degree  if  the  other  be  changed  inversely  in  the 
same  degree.  A  cannon-ball  weighing  1,000 
pounds,  and  moving  100  feet  per  second,  will 
have  1,560000  foot-pounds  of  energy;  but  a 
musket-ball  weighing  an  ounce  will  have  the 
same  amount  when  its  velocity  is  40,000  feet 
per  second.  Nevertheless,  another  body  act- 
ing upon  either  bullet  or  cannon-ball,  tending 
to  move  either  in  some  new  direction,  will  be 
as  efficient  while  those  bodies  are  moving  at 
any  assignable  rate  as  when  they  are  quiescent ; 
for  the  change  in  direction  will  depend  upon  the 
inertia  of  the  bodies,  arid  that  is  constant. 
The  common  theory  of  an  inert  body  is  one 


68  MODES  OF  MOTION 

that  is  wholly  passive,  having  no  power  of  itself 
to  move  or  do  anything  except  as  some  agency 
outside  itself  compels  it  to  move  in  one  way  or 
another,  and  thus  endows  it  with  energy.  Thus, 
a  stone  or  an  iron  nail  are  thought  to  be  inert 
bodies  in  that  sense  ;  and  it  is  true  that  either 
of  them  will  remain  in  one  place  for  an  indefinite 
time,  and  move  from  it  only  when  some  exter- 
nal agency  gives  them  impulse  and  direction. 
Still,  it  is  known  that  such  bodies  will  roll  down- 
hill if  they  will  not  roll  up,  and  it  has  itself  as 
much  to  do  with  the  down-hill  movement  as  the 
earth  has ;  that  is,  it  attracts  the  earth  as  much 
as  the  earth  attracts  it.  If  one  could  magnify 
the  structure  until  the  molecules  were  individ- 
ually visible,  every  one  of  them  would  be  seen 
to  be  in  intense  activity,  changing  its  form  and 
relative  position  an  enormous  number  of  times 
per  second  in  undirected  ways.  No  two  such 
molecules  move  in  the  same  way  at  the  same 
time ;  and  as  all  the  molecules  cohere  together, 
their  mutual  motions  in  different  directions 
balance  each  other,  so  the  body  as  a  whole  does 
not  change  its  position,  not  because  there  is  no 
moving  agency  in  itself,  but  because  the  indi- 
vidual movements  are  scattering,  and  not  in  a 
common  direction.  An  army  may  remain  in 
one  place  for  a  long  time.  To  one  at  a  distance 
it  is  quiescent,  inert.  To  one  in  the  camp 


INERTNESS  69 

there  is  abundant  sign  of  activity ;  but  the 
movements  are  individual  movements,  some  in 
one  direction  and  some  in  another,  and  often 
changing.  The  same  army  on  the  march  has 
the  same  energy,  the  same  rate  of  individual 
movement,  but  all  have  a  common  direction ;  it 
moves  as  a  whole  body  into  new  territory.  So 
with  the  molecules  of  matter.  In  large  masses 
they  appear  to  be  inert,  and  to  do  nothing,  and 
to  be  capable  of  doing  nothing.  That  is  only 
due  to  the  fact  that  their  energy  is  undirected, 
not  that  they  can  do  nothing.  The  inference 
that  if  quiescent  bodies  do  not  act  in  particu- 
lar ways  they  are  inert,  and  cannot  act  in  any 
kind  of  a  way,  is  a  wrong  inference.  An  illus- 
tration may  perhaps  make  this  point  plainer. 
A  lump  of  coal  will  be  still  as  long  as  anything 
if  it  be  undisturbed.  Indeed,  it  has  thus  lain 
in  a  coal-bed  for  millions  of  years  probably  ;  but 
if  coal  be  placed  where  it  can  combine  with 
oxygen,  it  forthwith  does  so,  and  during  the 
process  yields  a  large  amount  of  energy  in  the 
shape  of  heat.  One  pound  of  coal  in  this  way 
gives  out  14,000  heat  units,  which  is  the  equiv- 
alent of  11,000,000  foot-pounds  of  work,  and 
if  it  could  be  all  utilized,  would  furnish  a  horse- 
power for  five  and  a  half  hours.  Can  any  inert 
body  weighing  a  pound  furnish  a  horse-power 
for  half  a  day  ?  And  can  a  body  give  out  what 


7O  MODES  OF  MOTION 

it  has  not  got  ?  Are  gunpowder  and  nitrogly- 
cerine inert  ?  Are  bread  and  butter,  and  foods 
in  general,  inert  because  they  will  not  push  and 
pull  as  a  man  or  a  horse  may  ?  All  have  en- 
ergy, which  is  available  in  certain  ways  and 
not  in  others;  and  whatever  possesses  energy 
available  in  any  way  is  not  an  ideally  inert 
body. 

Lastly,  how  many  inert  bodies  together  will  it 
take  to  make  an  active  body  ?  If  the  question 
be  absurd,  then  all  the  phenomena  witnessed  in 
bodies  large  or  small  are  due  to  the  fact  that 
the  atoms  are  not  inert,  but  are  immensely  en- 
ergetic ;  and  their  inertia  is  the  measure  of  their 
rates  of  exchanging  energy. 

THE   ETHER    IS    INERTIATIVE    CONDITIONALLY. 

A  moving  mass  of  matter  is  brought  to  rest 
by  friction  because  it  imparts  its  motion  at  some 
rate  to  the  body  it  is  in  contact  with.  Gen- 
erally the  energy  is  transformed  into  heat,  but 
sometimes  it  appears  as  electrification.  Fric- 
tion is  only  possible  because  one  or  both  of  the 
bodies  possess  inertia.  That  a  body  may  move 
in  the  ether  for  an  indefinite  time  without  los- 
ing its  velocity  has  been  stated  as  reason  for 
believing  the  ether  to  be  frictionless.  If  it  be 
frictionless,  then  it  is  without  inertia,  else  the 


ETHI-'.K   INERTIA  7  I 

energy  of  the  earth  and  of  a  ray  of  light  would 
be  frittered  away.  A  ray  of  light  can  only  be 
transformed  when  it  falls  upon  molecules  which 
may  be  heated  by  it.  As  the  ether  cannot  be 
heated,  and  cannot  transform  translational  en- 
ergy, it  is  inertialess  for  such  a  form  of  motion 
and  its  embodied  energy. 

It  is  not  thus  with  other  forms  of  energy 
than  the  translational.  Atomic  and  molecular 
vibrations  are  so  related  to  the  ether  that  they 
are  transformed  into  waves,  which  are  con- 
ducted away  at  a  definite  rate.  This  shows 
that  such  property  of  inertia  as  is  possessed  by 
the  ether  is  selective,  and  not  like  that  of  mat- 
ter, which  is  equally  inertiative  under  all  con- 
ditions. Similarly  with  electric  and  magnetic 
phenomena :  it  is  capable  of  transforming  the 
energy  which  may  reside  as  stress  in  the  ether; 
and  other  bodies  moving  in  the  space  so  affected 
meet  with  frictional  resistance,  for  they  become 
heated  if  the  motion  be  maintained.  On  the 
other  hand,  there  is  no  evidence  that  the  body 
which  produces  the  electric  or  magnetic  stress 
suffers  any  degree  of  friction  on  moving  in  pre- 
cisely the  same  space.  A  bar  magnet,  rotating 
on  its  longitudinal  axis,  does  not  disturb  its 
own  field  ;  but  a  piece  of  iron  revolving  near  the 
magnet  will  not  only  become  heated,  but  will 
heat  the  stationary  magnet.  Much  experimen- 


72  MODES   OF  MOTION 

tal  work  has  been  done  to  discover,  if  possi- 
ble, the  relation  of  a  magnet  to  its  ether  field. 
As  the  latter'  is  not  disturbed  by  the  rotation 
of  the  magnet,  it  has  been  concluded  that  the 
field  does  not  rotate  ;  but  as  every  molecule  in 
the  magnet  has  its  own  field,  independent  of  all 
the  rest,  it  is  mechanically  probable  that  each 
such  field  does  vary  in  the  rotation,  but  among 
the  thousands  of  millions  of  such  fields  the 
average  strength  of  the  .field  does  not  vary 
within  measurable  limits.  Another  considera- 
tion is,  that  the  magnetic  field  itself  when  moved 
in  space  suffers  no  frictional  resistance.  There 
is  no  magnetic  energy  wasted  through  ether  in- 
ertia. These  phenomena  show  that  whether  or 
not  the  ether  exhibits  the  quality  called  inertia 
depends  upon  the  kind  of  matter  and  the  kind 
of  motion  it  has. 

18.     MATTER   IS   MAGNETIC. 

The  ordinary  phenomenon  of  magnetism  is 
shown  by  bringing  a  piece  of  iron  into  the 
neighborhood  of  a  so-called  magnet,  where  it  is 
attracted  by  the  latter,  and,  if  free  to  move,  will 
go  to  and  cling  to  the  magnet.  A  delicately 
suspended  magnetic  needle  will  be  affected 
appreciably  by  a  strong  magnet  at  the  distance 
of  several  hundred  feet.  As  the  strength  of 


73 

such  action  varies  inversely  as  the  square  of  the 
distance  from  the  magnet,  it  is  evident  there 
can  be  no  absolute  boundary  to  it.  At  a  dis- 
tance from  an  ordinary  magnet,  it  becomes  too 
weak  to  be  detected  by  our  methods,  not  that 
there  is  a  limit  to  it.  It  is  customary  to  think 
of  iron  as  being  peculiarly  endowed  with  mag- 
netic quality,  but  all  kinds  of  matter  possess  it 
in  some  degree.  Wood,  stone,  paper,  oats,  sul- 
phur, and  all  the  rest,  are  attracted  by  a  mag- 
net, and  will  stick  to  it  if  the  magnet  be  a 
strong  one.  Whether  a  piece  of  iron  itself 
exhibits  the  property  depends  upon  its  temper- 
ature ;  for  near  700  degrees  it  becomes  as  mag- 
netically indifferent  as  a  piece  of  copper  at 
ordinary  temperature.  Oxygen,  too,  at  —200 
degrees  adheres  to  a  magnet  like  iron. 

In  this,  as  in  so  many  other  particulars,  how 
a  piece  of  matter  behaves  depends  upon  its 
temperature ;  not  that  the  essential  qualities 
are  modified  in  any  degree,  but  temperature 
interferes  with  atomic  arrangement  and  aggre- 
gation, and  so  disguises  their  phenomena. 

As  every  kind  of  matter  is  thus  affected  by  a 
magnet,  the  manifestations  differing  but  in  de- 
gree, it  follows  that  all  kinds  of  atoms,  all  the 
elements,  are  magnetic;  an  inherent  property 
in  them  as  much  so  as  gravitation  or  inertia, 
apparently  a  quality  depending  upon  the  struc- 


74  MODES   OF  MOTION 

ture  of  the  atoms  themselves,  in  the  same  sense 
as  gravitation  is  thus  dependent,  as  it  is  not  a 
quality  of  the  ether. 

An  atom  must,  then,  be  thought  of  as  hav- 
ing polarity,  different  qualities  on  the  two  sides, 
and  possessing  a  magnetic  field  as  extensive  as 
space  itself.  The  magnetic  field  is  the  stress  or 
pressure  in  the  ether  produced  by  the  magnetic 
body.  This  ether  pressure  produced  by  a  mag- 
net may  be  as  great  as  a  ton  per  square  inch. 
It  is  this  pressure  that  holds  an  armature  to 
the  magnet.  As  heat  is  a  molecular  condition 
of  vibration,  and  radiant  energy  the  result  of  it, 
so  is  magnetism  a  property  of  molecules,  and  the 
magnetic  field  the  temporary  condition  in  the 
ether  which  depends  upon  the  presence  of  a 
magnetic  body.  We  no  longer  speak  of  the 
wave  motion  in  the  ether  which  results  from 
heat  as  heat,  but  call  it  radiation  or  ether- 
waves  ;  and  for  a  like  reason  the  magnetic  field 
ought  not  to  be  called  magnetism. 

THE    ETHER    IS    NON-MAGNETIC. 

A  magnetic  field  manifests  itself  in  a  way 
that  implies  that  the  ether  structure,  if  it  may 
be  said  to  have  any,  is  deformed,  —  deformed  in 
such  a  sense  that  another  magnet  in  it  tends  to 
set  itself  in  the  plane  of  the  stress  ;  that  is,  the 


ETHER   N OX-MAGNETIC  75 

magnet  is  twisted  into  a  new  position  to  ac- 
commodate itself  to  the  condition  of  the  medium 
about  it.  The  new  position  is  the  result  of 
the  reaction  of  the  ether  upon  the  magnet,  an 
ether  pressure  acting  at  right  angles  to  the  body 
that  produces  the  stress.  Such  an  action  is  so 
anomalous  as  to  suggest  the  propriety  of  modi- 
fying the  so-called  third  law  of  motion  ;  viz., 
action  and  reaction  are  equal  and  opposite,  add- 
ing that  sometimes  action  and  reaction  are  at 
right  angles. 

There  is  no  condition  or  property  exhibited 
by  the  ether  itself  which  shows  it  to  have  any 
such  characteristic  as  attraction,  repulsion,  or 
differences  in  stress,  except  where  its  condition 
is  modified  by  the  activities  of  matter  in  some 
way.  Itself  is  not  attracted  or  repelled  by  a 
magnet ;  that  is,  it  is  not  a  magnetic  body  in 
any  such  sense  as  matter  in  any  of  its  forms  is, 
and  therefore  cannot  properly  be  called  mag- 
netic. 

It  has  been  a  mechanical  puzzle  to  under- 
stand how  the  vibratory  motions  called  heat 
could  set  up  light-waves  in  the  ether,  on  ac- 
count of  the  absence  of  friction.  In  the  en- 
deavor to  conceive  it,  the  origin  of  sound-waves 
has  been  in  mind,  where  longitudinal  air-waves 
are  produced  by  the  vibrations  of  a  sounding 


76  MODES   OF  MOTION 

body,  and  molecular  impact  is  the  antecedent  of 
the  waves.  The  analogy  will  not  apply.  The 
following  exposition  may  be  helpful  in  grasping 
the  idea  of  such  transformation  and  change  of 
energy  from  matter  to  the  ether. 

Consider  a  straight  bar  permanent  magnet  to 
be  held  in  the  hand.  It  has  its  north  and  south 
poles  and  its  field,  the  latter  extending  in  every 
direction  to  an  indefinite  distance.  It  is  to  be 
considered  as  ether  stress  of  such  a  sort  as  to 
tend  to  set  other  magnets  in  it  in  new  positions. 
If,  at  a  distance  of  ten  feet,  there  were  a  deli- 
cately poised  magnet  needle,  every  change  in 
the  position  of  the  magnet  held  in  the  hand 
would  bring  about  a  change  in  the  position  of 
the  needle.  If  the  position  of  the  hand  mag- 
net were  completely  reversed,  so  the  south  pole 
faced  where  the  north  pole  faced  before,  the 
field  would  have  been  completely  reversed,  and 
the  poised  needle  would  have  been  pushed  by 
the  field  into  an  opposite  position.  If  the 
needle  were  a  hundred  feet  away,  the  change 
would  have  been  the  same,  except  in  amount. 
The  same  might  be  said  if  the  two  were  a  mile 
apart,  or  the  distance  of  the  moon,  or  any  other 
distance;  for  there  is  no  limit  to  an  ether  mag- 
netic field.  Suppose  the  hand  magnet  to  have 
its  direction  completely  reversed  once  in  a  sec- 
ond. The  whole  field,  and  the  direction  of  the 


ORIGIN   OF  ETHER-WAVES.  TJ 

stress,  would  necessarily  be  reversed  as  often. 
But  this  kind  of  change  in  stress  is  known^by 
experiment  to  travel  with  the  speed  of  light, 
186,000  miles  a  second  ;  the  disturbance  due 
to  the  change  of  position  of  the  magnet  'will, 
therefore,  be  felt  in  some  degree  throughout 
space.  In  a  second  and  a  third  it  will  have 
reached  the  moon,  and  a  magnet  there  will  be 
in  some  measure  affected  by  it.  If  there  were 
an  observer  there  with  a  delicate  enough  mag- 
net, he  could  be  witness  to  its  changes  once  a 
second,  for  the  same  reason  one  in  the  room 
could.  The  only  difference  would  be  one  of 
amount  of  swing.  It  is,  therefore,  theoretically 
possible  to  signal  to  the  moon  with  a  swing- 
ing magnet.  Suppose,  again,  that  the  magnet 
should  be  swung  twice  a  second,  there  would  be 
formed  two  waves,  each  one-half  as  long  as  the 
first.  If  it  should  swing  ten  times  a  second,  the 
waves  would  be  one-tenth  of  186,000  miles  long. 
If,  in  some  mechanical  way,  it  could  be  rotated 
186,000  times  a  second,  the  wave  would  be  but 
one  mile  long.  Artificial  ways  have  been  in- 
vented for  changing  this  magnetic  field  as  many 
as  100  million  times  a  second,  and  the  corre- 
sponding wave  is  less  than  a  foot  long.  The 
shape  of  a  magnet  does  not  necessarily  make  it 
weaker  or  stronger  as  a  magnet ;  but  if  the  poles 
are  near  together,  the  magnetic  field  is  denser 


78  MODES   OF  MOTION 

between  them  than  when  they  are  separated. 
The  ether  stress  is  differently  distributed  for 
every  change  in  the  relative  positions  of  the 
poles. 

A  common  U-magnet,  if  struck,  will  vibrate  like 
a  tuning-fork,  and  it  gives  out  a  definite  pitch. 
Its  poles  swing  towards  and  away  from  each 
other  at  uniform  rates,  and  the  pitch  of  the 
magnet  will  depend  upon  its  size,  thickness, 
and  the  material  it  is  made  of. 

Let  ten  or  fifteen  ohms  of  any  convenient- 
sized  wire  be  wound  upon  the  bend  of  a  com- 
mercial U-magnet.  Let  this  wire  be  connected 
to  a  telephone  in  its  circuit.  When  the  mag- 
net is  made  to  sound  like  a  tuning-fork,  the 
pitch  will  be  reproduced  in  the  telephone 
very  loudly.  If  another  magnet  with  a  differ- 
ent pitch  be  allowed  to  vibrate  near  the  for- 
mer, the  pitch  of  the  vibrating  body  will  be 
heard  in  the  telephone  ;  and  these  show  that 
the  changing  magnetic  field  reacts  upon  the 
quiescent  magnet,  and  compels  the  latter  to 
vibrate  at  the  same  rate.  The  action  is  an 
ether  action,  the  waves  are  ether  waves,  but 
they  are  relatively  very  long.  If  the  magnet 
makes  500  vibrations  a  second,  the  waves  will 
be  372  miles  long,  the  number  of  times  500  is 
contained  in  186,000  miles.  Imagine  the  mag- 
net to  become  smaller  and  smaller,  until  it  is 


ORIGIN  OF  LIGHT-WAVES  79 

the  size  of  an  atom,  the  one  fifty  millionth  of 
an  inch.  Its  vibratory  rate  would  be  propor- 
tionally increased,  and  changes  in  its  form  would 
still  bring  about  changes  in  its  magnetic  field. 
But  its  magnetic  field  is  practically  limitless, 
and  the  number  of  vibrations  per  second  is  to 
be  reckoned  as  millions  of  millions ;  the  waves 
are  correspondingly  short,  small  fractions  of  an 
inch.  When  they  are  as  short  as  the  one 
thirty-seven  thousandth  of  an  inch,  they  are 
capable  of  affecting  the  retina  of  the  eye,  and 
then  are  said  to  be  visible  as  red  light.  If 
the  vibratory  rate  be  still  higher,  and  the  cor- 
responding waves  be  no  more  than  one  sixty- 
thousandth  of  an  inch  long,  they  affect  the  ret- 
ina as  violet  light ;  and  between  these  limits 
there  are  all  the  waves  that  produce  a  complete 
spectrum.  The  atoms,  then,  shake  the  ether 
in  this  way  because  they  all  have  a  magnetic 
hold  upon  the  ether,  so  that  any  disturbance  of 
their  own  magnetism,  such  as  necessarily  comes 
when  they  collide,  reacts  upon  the  ether  for 
the  same  reason  that  a  large  magnet  acts  thus 
upon  it  when  its  poles  approach  and  recede 
from  each  other.  It  is  not  a  phenomenon  of 
mechanical  impact  or  frictional  resistance,  since 
neither  is  possible  in  the  ether. 


8O  MODES   OF  MOTION 

19.     MATTER   EXISTS   ZN   SEVERAL   STATES. 

Molecular  cohesion  exists  between  very  wide 
ranges.  When  strong,  so  if  one  part  of  a  body 
is  moved  the  whole  is  moved  in  the  same  way, 
without  breaking  continuity  or  the  relative  po- 
sitions of  the  molecules,  we  call  the  body  a  solid. 
In  a  liquid,  cohesion  is  greatly  reduced,  and  any 
part  of  it  may  be  deformed  without  materially 
changing  the  form  of  the  rest.  The  molecules 
are  free  to  move  about  each  other,  and  there 
is  no  definite  position  which  any  need  assume 
or  keep.  With  gases  the  molecules  are  without 
any  cohesion  ;  each  one  is  independent  of  every 
other  one,  collides  with  and  bounds  away  from 
others  as  free  elastic  particles  do.  Between 
impacts  it  moves  in  what  is  called  its  free  path, 
which  may  be  long  or  short  as  the  density  of 
the  gas  be  less  or  greater. 

These  differing  degrees  of  cohesion  depend 
upon  temperature  ;  for  if  the  densest  and  hard- 
est substances  are  sufficiently  heated  they  will 
become  gaseous.  This  is  only  another  way  of 
saying  that  the  states  of  matter  depend  upon 
the  amount  of  molecular  energy  present.  Solid 
ice  becomes  water  by  the  application  of  heat. 
More  heat  reduces  it  to  steam  ;  still  more  de- 
composes the  steam  molecules  into  oxygen  and 
hydrogen  molecules ;  and,  lastly,  still  more 


SECONDARY  PROPERTIES  8 1 

heat  will  decompose  these  molecules  into  their 
atomic  state,  complete  dissociation.  On  cool- 
ing, the  process  of  reduction  will  be  reversed 
until  ice  has  been  formed  again. 

Cohesive  strength  in  solids  is  increased  by 
reduction  of  temperature,  and  metallic  rods  be- 
come stronger  the  colder  they  are. 

No  distinction  is  now  made  between  cohesion 
and  chemical  affinity ;  and  yet  at  low  tempera- 
tures chemical  action  will  not  take  place,  which 
phenomenon  shows  there  is  a  distinction  be- 
tween molecular  cohesion  and  molecular  struc- 
ture. In  molecular  structure,  as  determined 
by  chemical  activity,  the  molecules  and  atoms 
are  arranged  in  definite  ways,  which  depend 
upon  the  rate  of  vibrations  of  the  components. 
The  atoms  are  set  in  definite  positions  to  con- 
stitute a  given  molecule.  But  atoms  or  mole- 
cules may  cohere  for  other  reasons,  gravitative 
or  magnetic,  and  relative  positions  would  be 
immaterial.  In  the  absence  of  temperature  a 
solid  body  would  be  solider  and  stronger  than 
ever,  while  a  gaseous  mass  would  probably  fall 
by  gravity  to  the  floor  of  the  containing  ves- 
sel like  so  much  dust.  The  molecular  structure 
might  not  be  changed,  for  there  would  be  no 
agency  to  act  upon  it  in  a  disturbing  way. 


82  MODES  OF  MOTION 

THE    ETHER   HAS    NO    CORRESPONDING    STATES. 

Degrees  of  density  have  already  been  ex- 
cluded, and  the  homogeneity  and  continuity  of 
the  ether  would  also  exclude  the  possibility  of 
different  states  at  all  comparable  with  such 
as  belong  to  matter.  As  for  cohesion,  it  is 
doubtful  if  the  term  ought  to  be  applied  to 
such  a  substance.  The  word  itself  seems  to  im- 
ply possible  separateness ;  and  if  the  ether  be  a 
single  indivisible  substance,  its  cohesion  must 
be  infinite,  and  is  therefore  not  a  matter  of  de- 
gree. The  ether  has  sometimes  been  consid- 
ered as  an  elastic  solid  ;  but  such  solidity  is 
comparable  with  nothing  we  call  solid  in  mat- 
ter, and  the  word  has  to  be  defined  in  a  special 
sense  in  order  that  its  use  may  be  tolerated 
at  all.  In  addition  to  this,  some  of  the  phe- 
nomena exhibited  by  it,  such  as  diffraction  and 
double  refraction,  are  quite  incompatible  with 
the  theory  that  the  ether  is  an  elastic  solid. 
The  reasons  why  it  cannot  be  considered  as  a 
liquid  or  gas  have  been  considered  previously. 

The  expression  states  of  matter  cannot  be 
applied  to  the  ether  in  any  such  sense  as  it  is 
applied  to  matter  ;  but  there  is  one  sense  when 
possibly  it  may  be  considered  applicable.  Let 
it  be  granted  that  an  atom  is  a  vortex  ring  of 
ether  in  the  ether,  then  the  state  of  being  in 


SHEARING-STRESS  83 

ring  rotation  would  suffice  to  differentiate  that 
part  of  the  ether  from  the  rest,  and  give  to  it 
a  degree  of  individuality  not  possessed  by  the 
rest  ;  and  such  an  atom  might  be  called  a  state 
of  ether.  In  like  manner,  if  other  forms  of 
motion,  such  as  transverse  waves,  circular  and 
elliptical  spirals,  or  other  kinds  of  waves,  exist 
in  the  ether,  then  such  movements  give  special 
character  to  the  part  thus  active,  and  it  would 
be  proper  to  speak  of  such  states  of  the  ether; 
but  even  thus  the  word  would  not  be  used  in 
the  same  sense  as  it  is  used  when  one  speaks 
of  the  states  of  matter  as  being  solid,  liquid, 
and  gaseous. 


20.     SOLID  MATTER  CAN  MAINTAIN  A  SHEARING- 
STRESS ;    LIQUIDS  AND  GASES  CANNOT. 

A  sliding-stress  applied  to  a  solid  deforms  it 
to  a  degree -which  depends  upon  the  stress  and 
the  degree  of  rigidity  the  body  has.  Thus,  if 
the  hand  be  placed  upon  a  closed  book  lying 
on  the  table,  and  pressure  be  so  applied  as  to 
move  the  upper  side  of  the  book,  but  not  the 
lower,  the  book  is  said  to  be  subject  to  a  shear- 
ing-stress. If  the  pressing  hand  has  a  twisting 
motion,  the  book  will  be  warped.  Any  solid 
may  be  thus  sheared  or  warped,  but  neither 
liquids  nor  gases  can  be  so  affected.  Molecu- 


84  MODES  OF  MOTION 

lar  cohesion  makes  it  possible  in  the  one,  and 
the  lack  of  it  impossible  in  the  others.  The 
solid  can  maintain  such  a  deformation  indefi- 
nitely long  if  the  pressure  does  not  rupture  its 
molecular  structure. 

THE   ETHER  CAN    MAINTAIN  A   SHEARING-STRESS. 

The  phenomena  in  a  magnetic  field  show 
that  the  stress  is  of  such  a  sort  as  to  twist  into 
a  new  directional  position  the  body  upon  which 
it  acts,  as  exhibited  by  a  magnetic  needle  ;  also 
as  indicated  by  the  transverse  vibrations  of  the 
ether  waves  ;  and  again  by  the  twist  given  to 
plane  polarized  light  when  moving  through  a 
magnetic  field.  These  are  all  interpreted  as 
indicative  of  the  direction  of  ether  stress,  as  be- 
ing similar  to  a  shearing-stress  in  solid  matter. 
The  fact  has  been  adduced  to  show  the  ether 
to  be  a  solid  ;  but  such  a  phenomenon  is  cer- 
tainly incompatible  with  a  liquid  or  gaseous 
ether.  This  kind  of  stress  is  maintained  in- 
definitely about  a  permanent  magnet ;  and  the 
mechanical  pressure  which  may  result  from  it 
is  a  measure  of  the  strength  of  the  magnetic 
field,  and  may  exceed  a  thousand  pounds  per 
square  inch. 


SENSATION  DEPENDS   ON  MATTER        85 


21.     OTHER   PROPERTIES    OF    MATTER. 

There  are  many  secondary  qualities  exhibited 
by  matter  in  some  of  its  forms,  such  as  hard- 
ness, brittleness,  maleability,  color,  etc.  ;  and 
the  same  ultimate  element  may  exhibit  itself  in 
the  most  diverse  ways,  as  is  the  case  with  car- 
bon, which  exists  as  lampblack,  charcoal,  graph- 
ite, jet,  anthracite,  and  diamond,  ranging  from 
the  softest  to  the  hardest  of  known  bodies. 
Then,  it  may  be  black  or  colorless.  Gold  is 
yellow,  copper  red,  silver  white,  chlorine  green, 
iodine  purple.  The  only  significance  any  or  all 
of  such  qualities  have  for  us  here  is,  that  the 
ether  exhibits  none  of  them.  There  is  neither 
hardness  nor  brittleness  nor  color  nor  any  ap- 
proach to  any  of  the  characteristics  for  the 
identification  of  elementary  matter. 


22.     SENSATION   DEPENDS    UPON    MATTER. 

However  great  the  mystery  of  the  relation 
of  body  to  mind,  it  is  quite  true  that  the  ner- 
vous system  is  the  mechanism  by  and  through 
which  all  sensation  comes,  and  that  in  our  ex- 
perience, in  the  absence  of  nerves  there  is  nei- 
ther sensation  nor  consciousness.  The  nerves 
themselves  are  but  complex  chemical  struc- 


86  MODES   OF  MOTION 

tures  ;  the  molecular  constitution  is  said  to 
embrace  as  many  as  twenty  thousand  atoms, 
chiefly  carbon,  hydrogen,  oxygen,  and  nitrogen. 
There  must  be  continuity  of  this  structure  too; 
for  to  sever  a  nerve  is  to  paralyze  all  beyond. 
If  all  knowledge  comes  through  experience, 
and  all  experience  comes  through  the  nervous 
system,  the  possibilities  depend  upon  the  mech- 
anism each  individual  is  provided  with  for  ab- 
sorbing from  his  environment  what  energies 
there  are  that  can  act  upon  the  nerves.  Touch, 
taste,  and  smell  imply  contact ;  sound  has  greater 
range  ;  and  sight  has  the  immensity  of  the  uni- 
verse for  its  field.  The  most  distant  but  visible 
star  acts  through  the  optic  nerve  to  present 
itself  to  consciousness.  It  is  not  the  ego  that 
looks  out  through  the  eyes,  but  it  is  the  uni- 
verse that  pours  in  upon  the  ego. 

Again,  all  the  known  agencies  that  act  upon 
the  nerves,  whether  for  touch  or  sound  or  sight, 
imply  matter  in  some  of  its  forms  and  activities 
to  adapt  the  energy  to  the  nervous  system. 
The  mechanism  for  the  perception  of  light  is 
complicated.  The  light  acts  upon  a  sensitive 
surface,  where  molecular  structure  is  broken 
up ;  and  this  disturbance  is  in  the  presence  of 
nerve  terminals,  and  the  sensation  is  not  in  the 
eye,  but  in  the  sensorium.  In  like  manner  for 
all  the  rest ;  so  one  may  fairly  say  that  matter  is 


KTI/KK   JA'SKNSIBLE  87 

the  condition  for  sensation,  and  in  its  aosence 
there  would  be  nothing  we  call  sensation. 


THE    ETHER    IS    INSENSIBLE    TO    NERVES. 

The  ether  is  in  great  contrast  with  matter  in 
this  particular.  There  is  no  evidence  that  in 
any  direct  way  it  acts  upon  any  part  of  the  ner- 
vous system  or  upon  the  mind.  It  is  probable 
that  this  lack  of  relation  between  the  ether  and 
the  nervous  system  is  the  chief  reason  why 
its  discovery  was  so  long  delayed,  as  the  me- 
chanical necessities  for  it  even  now  are  felt 
only  by  such  as  recognize  continuity  as  a  con- 
dition for  the  transmission  of  energy  of  what- 
ever kind  it  may  be.  Action  at  a  distance 
contradicts  all  experience,  is  philosophically  in- 
credible, and  is  repudiated  by  every  one  who 
once  perceives  that  energy  has  two  factors, 
substance  and  motion. 

Here  is  presented  a  list  of  twenty-two  of  the 
known  properties  of  matter  contrasted  with 
those  exhibited  by  the  ether.  In  none  of  them 
are  the  properties  of  the  two  identical,  and  in 
most  of  them  what  is  true  for  one  is  not  true 
for  the  other.  They  are  not  simply  different ; 
they  are  incomparable. 

From  the  necessities  of  the  case,  as  knowl- 


88  MODES  OF  MOTION 

edge  was  acquired,  and  terminology  was  essen- 
tial for  making  distinctions,  the  ether  has  been 
described  in  terms  applicable  to  matter ;  hence 
such  terms  as  mass,  solidity,  elasticity,  density, 
rigidity,  etc.,  which  have  a  definite  meaning,  and 
convey  definite  mechanical  conceptions  when 
applied  to  matter,  have  no  corresponding  mean- 
ing, and  convey  no  such  mechanical  conceptions, 
when  applied  to  the  ether.  It  is  certain  that 
they  are  inappropriate,  and  that  the  ether  and 
its  properties  cannot  be  described  in  terms 
applicable  to  matter.  Mathematical  considera- 
tions derived  from  the  study  of  matter  have  no 
advantage,  and  are  not  likely  to  lead  us  to  a 
knowledge  of  the  ether. 

Only  a  few  have  perceived  the  inconsistency 
of  thinking  of  the  two  in  the  same  terms.  In 
his  Grammar  of  Science,  Professor  Karl  Pier- 
son  says,  "  We  find  that  our  sense-impressions 
of  hardness,  weight,  color,  temperature,  cohe- 
sion, and  chemical  constitution,  may  all  be  de- 
scribed by  the  aid  of  the  motions  of  a  single 
medium,  which  itself  is  conceived  to  have  no 
hardness,  weight,  color,  temperature,  nor  in- 
deed elasticity  of  the  ordinary  conceptual  type." 

None  of  the  properties  of  the  ether  are  such 
as  one  would  or  could  have  predicted  if  he  had 
had  all  the  knowledge  possessed  by  mankind. 
Every  phenomenon  in  it  is  a  surprise  to  us,  be- 


OTHER   STRESSES  89 

cause  it  docs  not  follow  the  laws  which  experi- 
ence has  enabled  us  to  formulate  for  matter. 
A  substance  which  has  none  of  the  phenomenal 
properties  of  matter,  and  is  not  subject  to  the 
known  laws  of  matter,  ought  not  to  be  called 
matter.  Ether  phenomena  and  matter  phenom- 
ena belong  in  different  categories ;  and  the  ends 
of  science  will  not  be  conserved  by  confusing 
them,  as  is  done  when  the  same  terminology 
is  employed  for  both. 

There  are  other  properties  belonging  to  the 
ether  more  wonderful,  if  possible,  than  those 
already  mentioned,  —  its  ability  to  maintain 
enormous  stresses  of  various  kinds  without  the 
slightest  evidence  of  interference.  There  is 
the  gravitational  stress,  a  direct  pull  between 
two  masses  of  matter.  Between  two  molecules 
it  is  immeasurably  small,  even  when  close  to- 
gether; but  the^  prodigious  number  of  them  in  a 
bullet  brings  the  action  into  the  field  of  obser- 
vation, while  between  such  bodies  as  the  earth 
and  moon  or  sun  the  quantity  reaches  an  as- 
tonishing figure.  Thus,  if  the  gravitative  ten- 
sion due  to  the  gravitative  attraction  of  the 
earth  and  moon  were  to  be  replaced  by  steel 
wires  connecting  the  two  bodies  to  prevent  the 
moon  from  leaving  its  orbit,  there  would  be 
needed  four  No.  10  steel  wires  to  every  square 
inch  upon  the  earth ;  and  these  would  be  strained 


Cp  MODES   OF  MOTION 

nearly  to  the  breaking-point.  Yet  this  stress  is 
not  only  endured  continually  by  this  pliant,  im- 
palpable, transparent  medium,  but  other  bodies 
can  move  through  the  same  space  apparently  as 
freely  as  if  it  were  entirely  free.  In  addition 
to  this,  the  stress  from  the  sun  and  the  more 
variable  stresses  from  the  planets  are  all  en- 
dured by  the  same  medium  in  the  same  space  ; 
and  apparently  a  thousand  or  a  million  times 
more  would  not  make  the  slightest  difference. 
Rupture  is  impossible. 

Electric  and  magnetic  stresses  acting  parallel 
or  at  right  angles  to  the  other  exist  in  the  same 
space  and  to  indefinite  degrees,  neither  modi- 
fying the  direction  or  amount  of  either  of  the 
others. 

These  various  stresses  have  been  computed 
to  represent  energy  which,  if  it  could  be  util- 
ized, each  cubic  inch  of  space  would  yield  five 
hundred  horse-power.  It  shows  what  a  store- 
house of  energy  the  ether  is.  If  every  particle 
of  matter  were  to  be  instantly  annihilated,  the 
universe  of  ether  would  still  have  an  inexpressi- 
ble amount  of  energy  left.  To  draw  at  will  di- 
rectly from  this  inexhaustible  supply,  and  utilize 
it  for  the  needs  of  mankind,  is  not  a  forlorn 
hope. 

The  accompanying  table  presents  these  con- 
trasting properties  for  convenient  inspection  :  — 


TABLE   OF  CONTRASTED  PROPERTIES     91 


CONTRASTED  PROPERTIES  OF  MATTER   AND  THE 
ETHER. 


MATTER. 

ETHER. 

i.  Discontinuous  .     .     . 

:  Continuous 

2.  Limited    

:  Unlimited. 

3.  Heterogeneous       .     . 

:  Homogeneous. 

4.  Atomic     

:  Non-atomic. 

5.  Definite  structure  . 

:  Structureless. 

6.  Gravitative    .... 

:  Gravitationless. 

7.  Frictionable  .... 

:  Frictionless. 

8.  yEolotropic   .... 

:  Isotropic. 

9.  Chemically  selective   . 

•  (                            1 

•  \                            ) 

10.  Harmonically  related 

•   ( 

1  1  .  Energy  embodied  . 

•   \                            > 
:  Energy  endowed. 

12.  Energy  transformer     . 

:  Non-transformer. 

13- 


Elastic :  Elastic? 


:  Density? 

:  Unbeatable. 

:  Indestructible. 

:  Inertiative  conditionally. 


14.  Density    . 

15.  H  eatable.     .     . 

1 6.  Indestructible   . 

17.  Inertiative     .     . 

1 8.  Magnetic       .....:  ( —  — ). 

19.  Variable  states  .     .     .     :  ( • —  — ). 

20.  Shearing-stress  in  solid  :  Shearing-stress  maintained. 

21.  Secondary  qualities     .     :  ( —  — ). 

22.  Sensation  depends  upon  :  Insensible  to  nerves. 


92  MODES  OF  MOTION 


CHAPTER   III 

TRANSFORMATIONS    OF    MOTIONS. 

So  far  as  we  have  knowledge  to-day,  the  only 
factors  we  have  to  consider  in  explaining  physi- 
cal phenomena  are  :  (i)  ordinary  matter,  such 
as  constitutes  the  substance  of  the  earth  and 
the  heavenly  bodies ;  (2)  the  ether,  which  is  om- 
nipresent; and  (3)  the  various  forms  of  motion, 
which  are  mutually  transformable  in  matter,  and 
some  of  which,  but  not  all,  are  transformable 
into  ether  forms.  For  instance,  the  trans- 
latory  motion  of  a  mass  of  matter  can  be  im- 
parted to  another  mass  by  simple  impact,  but 
translatory  motion  cannot  be  imparted  to  the 
ether,  and,  for  that  reason,  a  body  moving  in  it 
is  not  subject  to  friction,  and  continues  to  move 
on  with  velocity  undiminished  for  an  indefinite 
time  ;  but  the  vibratory  motion  which  consti- 
tutes heat  is  transformable  into  wave  motion 
in  the  ether,  and  is  transmitted  away  with  the 
speed  of  light.  The  kind  of  motion  which  is 
thus  transformed  is  not  even  a  to-and-fro  swing 
of  an  atom  or  molecule,  like  the  swing  of  a 


TERMINOL  OGY  93 

pendulum-bob,  but  that  due  to  a  change  of  form 
of  the  atoms  within  the  molecule;  otherwise 
there  could  be  no  such  thing  as  spectrum  analy- 
sis. Vibratory  motion  of  the  matter  becomes 
undulatory  motion  in  the  ether.  The  vibratory 
motion  we  call  heat  ;  the  wave  motion  we  call 
sometimes  radiant  energy,  sometimes  light. 
Neither  of  these  terms  is  a  good  one,  but  we 
now  have  no  others. 

It  is  conceded  that  it  is  not  proper  to  speak 
of  the  wave  motion  in  the  ether  as  heat:  it  is 
also  admitted  that  the  ether  is  not  heated  by  the 
presence  of  the  wave  ;  or,  in  other  words,  the 
temperature  of  the  ether  is  absolute  zero.  Mat- 
ter only  can  be  heated.  But  the  ether-waves 
can  heat  other  matter  they  may  fall  on  ;  so  there 
are  three  steps  in  the  process,  and  two  trans- 
formations:  (i)  vibrating  matter;  (2)  waves 
in  the  ether  ;  (3)  vibration  in  other  matter. 
Energy  has  been  transferred  indirectly.  What 
I  want  to  impress  in  this  is,  when  a  form  of 
energy  in  matter  is  transformed  in  any  manner 
so  as  to  lose  its  characteristics,  it  is  not  proper  to 
call  it  by  the  same  name  after  the  transformation 
as  before ;  and  this  we  do  in  all  cases  when  the 
transformation  is  from  one  kind  in  matter  to 
another  kind  in  matter.  Thus,  when  a  bullet  is 
shot  against  a  target,  before  it  strikes,  it  has 
what  we  call  mechanical  energy,  and  we  meas- 


94  MODES  OF  MOTION 

ure  that  in  foot-pounds ;  after  it  has  struck  the 
target,  the  transformation  is  into  heat,  and  this 
has  its  mechanical  equivalent,  but  is  not  called 
mechanical  energy,  nor  are  the  motions  which 
embody  it  similar.  The  mechanical  ideas  in 
these  phenomena  are  easy  to  grasp.  They  ap- 
ply to  the  phenomena  of  the  mechanics  of  large 
and  small  bodies,  to  sound,  to  heat,  and  to  light, 
as  ordinarily  considered  ;  but  they  have  not  been 
applied  to  electric  phenomena,  as  they  evidently 
should  be,  unless  it  be  held  that  such  phenom- 
ena are  not  related  to  ordinary  phenomena,  as 
the  latter  are  to  one  another. 

When  we  would  give  a  complete  explanation 
of  the  phenomena  exhibited  by,  say,  a  heated 
body,  we  need  to  inquire  as  to  the  antecedents 
of  the  manifestation,  and  also  its  consequents. 
Where  and  how  did  it  get  its  heat  ?  Where 
and  how  did  it  lose  it  ?  When  we  know  every 
step  of  those  processes,  we  know  all  there  is  to 
learn  about  them.  Let  us  undertake  the  same 
thing  for  some  electrical  phenomena. 

First,  under  what  circumstances  do  electrical 
phenomena  arise? 

(i.)  Mechanical,  as  when  two  different  kinds 
of  matter  are  subject  to  friction. 

(2.)  Thermal,  as  when  two  substances  in 
molecular  contact  are  heated  at  the  junction. 

(3.)  Magnetic,  as  when  any  conductor  is  in 
a  changing  magnetic  field. 


TRAA7SFORMA  TIONS 


95 


(4.)  Chemical,  as  when  a  metal  is  being  dis- 
solved in  any  solution. 

(5.)  Physiological,  as  when  a  muscle  con- 
tracts. 

Each  of  these  has  several  varieties ;  and 
changes  may  be  rung  on  combinations  of  them, 


Fig.  5.     Frictional  Electrical  Machine. 


as  when  mechanical  and  magnetic  conditions 
interact. 

(i.)  In  the  first  case,  ordinary  mechanical 
or  translational  energy  is  spent  as  friction,  an 
amount  measurable  in  foot-pounds,  and  the  fac- 
tors we  know,  a  pressure  into  a  distance.  If 
the  surfaces  be  of  the  same  kind  of  molecules, 
the  whole  energy  is  spent  as  heat,  and  is  pres- 
ently radiated  away.  If  the  surfaces  are  of  un- 
like molecules,  the  product  is  a  compound  one, 


MODES  OF  MOTION 


part  heat,  part  electrical.  What  we  have  turned 
in  we  know  to  be  a  particular  mode  of  motion. 
We  have  not  changed  the  amount  of  matter  in- 
volved ;  indeed,  we  assume,  without  specifying 
and  without  controversy,  that  matter  is  itself 
indestructible,  and  the  product,  whether  it  be 
of  one  kind  or  another,  can  only  be  some  form 
of  motion.  Whether  we  can  describe  it  or 
not  is  immaterial ;  but  if  we  agree  that  heat  is 
vibratory  molecular  motion,  and  there  be  any 
other  kind  of  a  product  than  heat,  it,  too,  must 
also  be  some  other  form  of  motion.  So,  if  one 
is  to  form  a  concep- 
tion of  the  mechani- 
cal origin  of  electri- 
city, this  is  the  only 
one  he  can  have,  — 
transformed  motion. 
(2.)  When  heat 
is  the  antecedent  of 
electricity,  as  in  the 
thermopile,  that 
which  is  turned  into 
the  pile  we  know  to 
be  molecular  motion 
of  a  definite  kind. 
That  which  comes 

out  of  it  must  be  some  equivalent  motion  ;  and 
if  all  that  went  into  it  were  transformed,  then 


Fig,  6.     Thermopile. 


TRANSFORMATIONS  97 

all  that  came  out  would  be  transformed,  call  it 
by  what  name  we  will,  and  let  its  amount  be 
what  it  may. 

(3.)  When  a  conductor  is  moved  in  a  mag- 
netic field,  the  energy  spent  is  measurable  in 
foot-pounds,  as  before,  a  pressure  into  a  dis- 


Fig.  7.    Dynamo. 

tance.  The  energy  appears  in  a  new  form,  but 
the  quantity  of  matter  being  unchanged,  the 
only  changeable  factor  is  the  kind  of  motion  ; 
and  that  the  motion  is  molecular  is  evident,  for 
the  molecules  are  heated.  Mechanical  or  mass 


98 


MODES   OF  MOTION 


motion  is  the  antecedent,  molecular  heat  mo- 
tion is  the  consequent ;  and  the  way  we  know 
there  has  been  some  intermediate  form  is  that 
heat  is  not  conducted  at  the  rate  which  is  ob- 
served in  such  a  case.  Call  it  by  what  name 
one  will,  some  form  of  motion  has  been  imme- 
diate between  the  antecedent  and  the  conse- 
quent, else  we  have  some  other  factor  of  energy 
to  reckon  with  than  ether,  matter,  and  motion. 
(4.)  In  a  galvanic  battery  the  source  of  elec- 
tricity is  chemical  action  ;  but  what  is  chemical 
action  ?  Simply  an  exchange  of  the  constitu- 
ents of  molecules,  a  change 
which  involves  exchange  of 
energy.  Molecules  capable 
of  doing  chemical  work  are 
loaded  with  energy.  The 
chemical  product's  of  battery 
action  are  molecules  of  dif- 
ferent constitution,  with 
smaller  amounts  of  en- 
ergy as  measured  in  cal- 
ories, or  heat  units. 
If  the  results  of  the 
chemical  reaction  be 
prevented  from  escap- 

Fig.  8.     Galvanic  Battery.  ing  by  Confining  them 

to  the  cell  itself,  the 
whole  energy  appears  as  heat,  and  raises  the 


TKANSFORMA  TIONS 


99 


temperature  of  the  cell.  If  a  so-called  circuit 
be  provided,  the  energy  is  distributed  through 
it,  and  less  heat  is  spent  in  the  cell  ;  but 
whether  it  be  in  one  place  or  another,  the 
mass  of  matter  involved  is  not  changed,  arid 
the  variable  factor  is 
the  motion,  the  same 
as  in  the  other  cases. 
The  mechanical  con- 
ceptions appropriate 
are  the  transforma- 
tion of  one  kind  of 
motion  into  another 
kind  by  the  mechan- 
ical conditions  pro- 
vided. 

(5.)  Physiological 
antecedents  of  electri- 
city are  exemplified  by 
the  structure  and  mode 
of  operation  of  certain 
muscles,  a,  in  the  tor- 
pedo (Fig.  9)  and  other 
electrical  animals.  The 
mechanical  contraction 
of  them  results  in  an  Fig.  9.  Torpedo. 

electrical     excitation, 

and,  if  a  proper  circuit  be  provided,  in  an  elec- 
tric current.      The  energy  of   a  muscle  is  de- 


IOO  MODES  OF  MOTION 

rived  from  food,  which  is  itself  but  a  molecular 
compound  loaded  with  energy  of  a  kind  avail- 
able for  muscular  transformation.  Bread  and 
butter  has  more  available  energy,  pound  for 
pound,  than  has  coal,  and  can  be  substituted 
for  coal  for  running  an  engine.  It  is  not  used 
because  it  costs  so  much  more.  There  is  noth- 
ing different,  so  far  as  the  factors  of  energy  go, 
between  the  food  of  an  animal  and  the  food  of 
an  engine.  What  becomes  of  the  energy  de- 
pends upon  the  kind  of  structure  it  acts  on. 
It  may  be  changed  into  translatory,  and  the 
whole  body  moves  in  one  direction  ;  or  into 
molecular,  and  then  appears  as  heat  or  electri- 
cal energy. 

If  one  confines  his  attention  to  the  only  va- 
riable factor  in  the  energy  in  all  these  cases, 
and  traces  out  in  each  just  what  happens,  he 
will  have  only  motions  of  one  sort  or  another,  at 
one  rate  or  another ;  and  there  is  nothing  more 
mysterious  which  enters  into  the  processes. 

We  will  turn  now  to  how  electricity  mani- 
fests itself,  and  what  it  can  do.  It  may  be 
well  to  point  out  at  the  outset  what  has  occa- 
sionally been  stated,  but  which,  in  my  judg- 
ment, has  not  received  the  philosophical 
attention  it  deserves ;  namely,  that  electrical 
phenomena  are  reversible,  —  that  is,  any  kind 


TRANS  FOR  MA  TIONS 


IOI 


of  a  physical  process  which  is  capable  of  pro- 
ducing electricity,  electricity  is  itself  able  to 
produce.  Thus  to  name  a  few  :  If  mechanical 
motion  develops  electricity,  electricity  will  pro- 
duce mechanical'  motion  ;  the  movement  of  a 
pith-ball  and  an  electric  motor  are  examples. 
If  chemical  action  can  produce  it,  it  will  pro- 


MOT  ox 


Fig.  70.    Electric  Motor. 


duce  chemical  action,  as  in  the  decomposition 
of  water  and  electroplating.  As  heat  may  be 
its  antecedent,  so  will  it  produce  heat.  If  mag- 
netism be  an  antecedent  factor,  magnetism  may 
be  its  product.  What  is  called  induction  may 
give  rise  to  it  in  an  adjacent  conductor;  and, 
likewise,  induction  may  be  its  effect. 

Let  us  suppose  ourselves  to  be  in  a  building 
in  which  a  steam-engine  is  at  work.  There  is 
fuel,  the  furnace,  the  boiler,  the  pipes,  the  en- 
gine with  its  fly-wheel  turning.  The  fuel  burns 
in  the  furnace,  the  water  is  superheated  in  the 


IO2  MODES  OF  MOTION 

boiler,  the  steam  is  directed  by  the  pipes,  the 
piston  is  moved  by  the  steam  pressure,  and 
the  fly-wheel  rotates  because  of  proper  mechan- 
ism between  it  and  the  piston.  No  one  who 
has  given  attention  to  the  successive  steps  in 
the  process  is  so  puzzled  as  to  feel  the  need  of 
inventing  a  particular  force,  or  a  new  kind  of 
matter,  or  any  agency,  at  any  stage  of  the  pro- 
cess, different  from  the  simple  mechanical  ones 
represented  by  a  push  or  a  pull.  Even  if  he 
cannot  see  clearly  how  heat  can  produce  a 
push,  he  does  not  venture  to  assume  a  genii  to 
do  the  work,  but  for  the  time  is  content  with 
saying  that  if  he  starts  with  motion  in  the  fur- 
nace, and  stops  with  the  motion  of  the  fly- 
wheel, any  assumption  of  any  other  factor  than 
some  form  of  motion  between  the  two  would 
be  gratuitous.  He  can  truthfully  say  that  he 
understands  the  nature  of  that  which  goes  be- 
tween the  furnace  and  the  wheel ;  that  it  is 
some  sort  of  motion,  the  particular  kinds  of 
which  he  might  make  out  at  his  leisure. 

Suppose,  once  more,  that  across  the  highway 
from  this  engine-house  there  is  another  build- 
ing, where  all  sorts  of  machines  —  lathes,  pla- 
ners, drills,  etc.  —  are  running,  but  that  the 
source  of  the  power  for  all  this  is  out  of  sight, 
and  that  one  can  see  no  connection  between 
this  and  the  engine  on  the  other  side  of  the 


TRA  NSFORMA  TIONS  1 03 

street.  Would  one  need  to  suppose  there  was 
anything  mysterious  between  the  two  —  a  force, 
a  fluid,  an  immaterial  something  ?  I  am  asking 
the  question  on  the  supposition  that  one  was 
not  aware  of  the  shaft  that  might  be  between 
the  two  buildings,  and  that  it  was  not  obvious 
on  simple  inspection  how  the  machines  got 
their  motions  from  the  engine.  I  think  no  one 
would  be  puzzled  because  he  did  not  know  just 
what  the  intervening  mechanism  might  be.  If 
the  boiler  were  in  the  one  building,  and  the 
engine  in  the  other  with  the  machines,  he  could 
see  nothing  moving  between  them,  even  if  the 
steam-pipes  were  of  glass.  If  matter  of  any 
kind  were  moving,  he  could  not  see  it  there. 
He  would  say  there  must  be  something  moving, 
or  pressure  could  not  be  transferred  from  the 
one  place  to  the  other. 

Substitute  for  the  furnace  and  boiler  a  gal- 
vanic battery  or  a  dynamo  ;  for  the  machines 
of  the  shop,  one  or  more  motors  with  suitable 
wire  connections.  When  the  dynamo  goes,  the 
motors  go  ;  when  the  dynamo  stops,  the  motors 
stop ;  nothing  can  be  seen  to  be  turning  or  mov- 
ing in  any  way  between  them.  Is  there  any 
necessity  for  assuming  a  mysterious  agency,  or 
a  force  of  a  nature  different  from  the  visible 
ones  at  the  two  ends  of  the  line  ?  Is  it  not 
certain  that  the  question  is,  How  does  the  mo- 


104  MODES  OF  MOTION 

tion  get  from  the  one  to  the  other,  whether 
there  be  a  wire  or  not  ?  If  there  be  a  wire, 
it  is  plain  that  there  is  motion  in  it ;  for  it  is 
heated  its  whole  length,  and  heat  is  known  to 
be  a  mode  of  motion,  and  every  molecule  which 
is  thus  heated  must  have  had  some  antecedent 
motions.  Whether  it  be  defined  or  not,  and 
whether  it  be  called  by  one  name  or  another, 
are  quite  immaterial  if  one  is  concerned  only 
with  the  nature  of  the  action,  whether  it  be 
matter  or  ether,  or  motion  or  abracadabra. 

Once  more  :  suppose  we  have  a  series  of  ac- 
tive machines.  An  arc  lamp,  radiating  light- 
waves, gets  its  energy  from  the  wire  which  is 
heated,  which  in  turn  gets  its  energy  from  the 


Fig    1 1 

electric  current,  that  from  a  dynamo,  the  dy- 
namo from  a  steam-engine,  that  from  a  furnace 
and  the  chemical  actions  going  on  in  it.  Let 
us  call  the  chemical  actions  A,  the  furnace  B, 
the  engine  C,  the  dynamo  D,  the  electric  lamp 
E,  the  ether- waves  F.  (Fig.  n.) 

The  product  of  the  chemical  action  of  the 
coal  is  molecular  motion  called  heat  in  the  fur- 


TRANSFORMA  TIONS 


105 


nace.     The  product  of  the  heat  is  mechanical 
motion   in    the  engine.      The   product   of   the 
mechanical  motion  is  elec- 
tricity   in    the    dynamo. 
The    product  of  the  elec-      Co«Lplt£ 
trie   current    in    the  lamp 
is  light-waves  in  the  ether. 
Nobody    hesitates   for   an 
instant    to    speak    of    the 
heat   as   being    molecular 
motion,  nor  of  the  motions 
of    the    engine    as    being 
mechanical;  but  when  we 
come  to  the  product  of  the 
dynamo,    which   we  call 
electricity,  behold !  nearly 
every  one  says,   not   that 
he  does  not  know  what  it 
is,  but  that  no  one  knows. 
Does  any  one  venture  to 
say  he   does    not    know 
what  heat   is,  because  he 
cannot  describe   in   detail 
just    what    goes    on    in   a 
heated    body   as    it    might    be  de- 
scribed   by  one   who    saw  with   a 
microscope  the  movements  of  the 
molecules  ?     Let  us  go  back  for  a 
moment  to  the  proposition  stated  early  in  the 


106  MODES  OF  MOTION 

address ;  namely,  that  if  any  body  of  any  mag- 
nitude moves,  it  is  because  some  other  body 
in  motion,  and  in  contact  with  it,  has  imparted 
its  motion  by  mechanical  pressure.  Therefore 
the  ether-waves  at  F  (Fig.  n)  imply  continu- 
ous motions  of  some  sort  from  A  to  F.  That 
they  are  all  motions  of  ordinary  matter  from 
A  to  E  is  obvious,  because  continuous  mat- 
ter is  essential  for  the  maintenance  of  the 
actions.  At  E  the  motions  are  handed  over 
to  the  ether,  and  they  are  radiated  away  as 
light-waves. 

A  puzzling  electrical  phenomenon  has  been 
what  has  been  called  its  duality,  states  which 
are  spoken  of  as  positive  and  negative.  Thus, 
we  speak  of  the  positive  plate  of  a  battery,  and 
the  negative  pole  of  a  dynamo;  and  another 
troublesome  condition  to  idealize  has  been,  how 
it  could  be  that,  in  an  electric  circuit,  there 
could  be  as  much  energy  at  the  most  remote 
part  as  at  the  source.  But  if  one  will  take  a 
limp  rope,  eight  or  ten  feet  long,  tie  its  ends  to- 
gether, and  then  begin  to  twist  it  at  any  point, 
he  will  see  the  twist  move  in  a  right-handed 
spiral  on  the  one  hand,  and  in  a  left-handed 
spiral  on  the  other,  and  each  may  be  traced 
quite  round  the  circuit ;  so  there  will  be  as  much 
twist,  as  much  motion,  and  as  much  energy,  in 
one  part  of  the  rope  as  in  any  other  :  and  if  one 


TRAATSFORMA  TIONS 


107 


chooses  to  call  the  right-handed  twist  positive, 
and  the  left-handed  twist  negative,  he  will  have 
the  mechanical  phenomenon  of  energy  distribu- 
tion and  the  terminology  analogous  to  what 
they  are  in  an  electric  conductor.  One  may  ask, 


Fig.  13.    Positive  and  Negative  Twist. 

Are  not  the  cases  more  dissimilar  than  the  me- 
chanical analogy  would  make  them  seem  to  be? 
Are  there  any  phenomena  which  imply  that 
rotation  is  going  on  in  an  electric  conductor  ? 
There  are.  An  electric  arc,  which  is  a  current 
in  the  air,  and  is,  therefore,  less  constrained 


IO8  MODES   OF  MOTION 

than  it  is  in  a  conductor,  rotates.  Especially 
marked  is  this  when  in  front  of  the  pole  of  a 
magnet ;  but  the  rotation  may  be  noticed  in  an 
ordinary  arc  by  looking  at  it  with  a  stroboscopic 
disk,  rotated  so  as  to  make  the  light  to  the  eye 
intermittent  at  the  rate  of  four  or  five  hundred 
per  second.  A  ray  of  plane  polarized  light, 
parallel  with  a  wire  conveying  a  current,  has 
its  plane  of  vibration  twisted  to  the  right  or 
left  as  the  current  goes  one  way  or  the  other 
through  the  wire,  and  to  a  degree  that  depends 
upon  the  distance  it  travels ;  not  only  that,  but 
if  the  ray  be  sent  by  reflection  back  through 
the  same  field,  it  is  twisted  as  much  more,  —  a 
phenomenon  which  convinces  one  that  rotation 
is  going  on  in  the  space  through  which  the  ray 
travels.  If  the  ether  through  which  the  ray  be 
sent  were  simply  warped,  or  in  some  static  stress, 
the  ray,  after  reflection,  would  be  brought  back 
to  its  original  plane,  which  is  not  the  case. 
This  rotation  in  the  ether  is  produced  by  what 
is  going  on  in  the  wire.  .  The  ether-waves  called 
light  are  interpreted  to  imply  that  molecules 
originate  them  by  their  vibrations,  and  that 
there  are  as  many  ether-waves  per  second  as  of 
molecular  vibrations  per  second.  In  like  man- 
ner, the  implication  is  the  same,  that  if  there  be 
rotations  in  the  ether,  they  must  be  produced 
by  molecular  rotation,  and  there  must  be  as 


ROTAl^IONS  ICQ 

many  rotations  per  second  in  the  ether  as  there 
are  molecular  rotations  that  produce  them.  The 
space  about  a  wire  carrying  a  current  is  often 
pictured  as  filled  with,  whorls  indicating  this 
motion  (Fig.  14);  and  one  must  picture  to  him- 
self, not  the  wire  as  a  whole  rotating,  but  each 


Fig.  14. 

individual  molecule  independently.  But  one  is 
aware  that  the  molecules  of  a  conductor  are 
practically  in  contact  with  each  other,  and  that 
if  one  for  any  reason  rotates,  the  next  one  to  it 
would,  from  frictional  action,  cause  the  one  it 
touched  to  rotate  in  the  opposite  direction, 
whereas,  the  evidence  goes  to  show  that  all 
rotation  is  in  the  same  direction. 

How  can  this  be  explained  mechanically  ? 
Recall  the  kind  of  action  that  constitutes  heat, 
that  it  is  not  translatory  action  in  any  degree, 
but  vibratory,  in  the  sense  of  a  change  of  form 
of  an  elastic  body;  and  this,  too,  of  the  atoms 
that  make  up  the  molecule,  of  whatever  sort. 
Each  atom  is  so  far  independent  of  every  other 
atom  in  the  molecule  that  it  can  vibrate  in  this 
way,  else  it  could  not  be  heated.  The  greater 


I  10  MODES  OF  MOTION 

the  amplitude  of  vibration,  the  more  free  space 
to  move  in;  and  continuous  contact  of  atoms  is 
incompatible  with  the  mechanics  of  heat.  There 
must,  therefore,  be  impact  and  freedom  alter- 
nating with  each  other  in  all  degrees  in  a 
heated  body.  If,  in  any  way,  the  atoms  them- 
selves were  made  to  rotate,  their  heat  impacts 
not  only  would  restrain  the  rotations,  but  the 
energy  also  of  the  rotation  motion  would  in- 
crease the  vibrations  ;  that  is,  the  heat  would 
be  correspondingly  increased,  which  is  what 
happens  always  when  an  electric  current  is  in  a 
conductor.  It  appears  that  the  cooler  a  body  is, 
the  less  electric  resistance  it  has,  and  the  indi- 
cations are  that  at  absolute  zero  there  is  no 
resistance  ;  that  is,  impacts  do  not  retard  rota- 
tion :  but  it  is  also  apparent  that  any  current 
sent  through  a  conductor  at  that  temperature 
would  at  once  heat  it.  This  is  the  same  as 
saying  that  an  electric  current  could  not  be 
sent  through  a  conductor  at  absolute  zero. 

So  far  mechanical  conceptions  are  in  accord- 
ance with  electrical  phenomena,  but  there  are 
several  others  yet  to  be  noted.  I  have  spoken 
of  electrical  phenomena  as  molecular  or  atomic 
phenomena ;  and  there  is  one  more  in  that  cate- 
gory which  is  well  enough  known,  and  which  is 
so  important  and  suggestive  that  I  wonder  its 
significance  has  not  been  seen  by  those  who 


ELECTRICAL   ACTION  III 

have  sought  to  interpret  electrical  phenomena. 
I  refer  to  the  fact  that  electricity  cannot  be 
transmitted  though  a  vacuum.  An  electric 
arc  begins  to  spread  out  as  the  density  of  the 
air  decreases,  and  presently  it  is  extinguished. 
An  induction  spark  that  will  jump  two  or  three 
feet  in  air  cannot  be  made  to  bridge  the  tenth  of 
an  inch  in  an  ordinary  vacuum.  A  vacuum  is  a 
perfect  non-conductor  of  electricity.  Is  there 
more  than  one  possible  interpretation  to  this; 
namely,  that  electricity  is  fundamentally  a  mo- 
lecular and  atomic  phenomenon,  and  in  the  ab- 
sence of  molecules  cannot  exist  ?  One  may 
say  :  "  Electrical  action  is  not  hindered  by  a 
vacuum  ;"  which  is  true,  but  has  quite  another 
interpretation  than  the  implication  that  electri- 
city is  an  ether  phenomenon. 

The  heat  of  the  sun  in  some  way  gets  to  the 
earth,  but  what  takes  place  in  the  ether  is  not 
heat  transmission.  There  is  no  heat  in  space, 
and  no  one  is  at  liberty  to  say  or  think  that 
there  can  be  heat  in  the  absence  of  matter. 
When  heat  has  been  transformed  into  ether- 
waves  it  is  no  longer  heat,  call  it  by  what  name 
one  will.  Formerly  such  waves  were  called 
heat-waves ;  no  one  properly  informed  does 
that  now.  In  like  manner,  if  electrical  motions 
or  conditions  in  matter  be  transformed,  no  mat- 
ter how,  it  is  no  longer  proper  to  speak  of  such 


1 1 2  MODES   OF  MO  7V 'ON 

transformed  motions  or  conditions  as  electri- 
city. Thus,  if  electrical  energy  be  transformed 
into  heat,  no  one  thinks  of  speaking  of  the 
latter  as  electrical.  If  the  electrical  energy  be 
transformed  into  mechanical  of  any  sort,  no 
one  thinks  of  calling  the  latter  electrical  be- 
cause of  its  antecedent.  If  electrical  motions 
be  transformed  into  ether  actions  of  any  kind, 
why  should  we  continue  to  speak  of  the  trans- 
formed motions  or  energy  as  being  electrical  ? 
Electricity  may  be  the  antecedent,  in  the  same 
sense  as  mechanical  motion  of  a  bullet  may  be 
the  antecedent  of  the  heat  developed  when  the 
latter  strikes  the  target  ;  and  if  it  be  granted 
that  a  vacuum  is  a  perfect  non-conductor  of 
electricity,  then  it  is  manifestly  improper  to 
speak  of  any  phenomenon  in  the  ether  as  an 
electrical  phenomenon.  It  is  from  the  failure 
to  make  this  distinction  that  most  of  the  trouble 
has  come  in  thinking  on  this  subject.  Some 
have  given  all  their  attention  to  what  goes  on 
in  matter,  and  have  called  that  electricity  ; 
others  have  given  their  attention  to  what  goes 
on  in  the  ether,  and  have  called  that  electricity ; 
and  some  have  considered  both  as  being  the 
same  thing,  and  have  been  confounded.  In 
this  sense  an  arc  light  is  no  more  an  electric 
light  than  is  that  from  a  tallow  candle. 


CONSTITUTION'  OF  A  TOMS  I  1 3 

Let  us  consider  what  is  the  relation  between 
an  electrified  body  and  the  ether  about  it. 

When  a  body  is  electrified,  the  latter  at  the 
same  time  creates  an  ether  stress  about  it, 
which  is  called  an  electric  field.  The  ether 
stress  may  be  considered  as  a  warp  in  the  dis- 
tribution of  the  energy  about  the  body  (Fig. 
15)  by  the  new  positions  given  to  the  molecules 
by  the  process  of  electrification.  I  have  already 
said  that  the  evidence  from  other  sources  is 
that  atoms,  rather  than  molecules,  in  larger 
masses,  are  what  affect  the  ether.  One  needs 


ftEUTflAL   STRESS  POSITIVE  STRESS.  M£GflTIV£  STffCSS 

Fig.  15. 

to  inquire  for  what  knowledge  we  have  as  to 
the  constitution  of  matter  or  of  atoms. 

There  is  only  one  hypothesis  to-day  that  has 
any  degree  of  probability  ;  that  is  the  vortex- 
ring  theory,  which  describes  an  atom  as  being 
a  vortex  ring  of  ether  in  the  ether.  It  possesses 
a  definite  amount  of  energy  in  virtue  of  the 


114  MODES  OF  MOTION 

motion  which  constitutes  it  ;  and  this  motion 
differentiates  it  from  the  surrounding  ether, 
giving  it  dimensions,  elasticity,  momentum,  and 
the  possibility  of  translatory,  rotary,  and  vibra- 
tory motions  and  combinations  of  them.  With- 
out going  farther  into  this,  it  is  sufficient,  for  a 
mechanical  conception,  that  one  should  have  so 
much  in  mind,  as  it  will  vastly  help  in  forming 
a  mechanical  conception  of  reactions  between 
atoms  and  the  ether.  An  exchange  of  energy 
between  such  an  atom  and  the  ether  is  not 
an  exchange  between  different  kinds  of  things, 
but  between  different  conditions  of  the  same 
thing.  Next,  it  should  be  remembered  that  all 
the  elements  are  magnetic  in  some  degree. 
This  means  that  they  are  themselves  magnets  ; 
and  every  magnet  has  a  magnetic  field,  unlim- 
ited in  extent,  which  can  almost  be  regarded  as 
a  part  of  itself.  If  a  magnet  of  any  size  be 
moved,  its  field  is  moved  with  it ;  and  if  in  any 
way  the  magnetism  be  increased  or  diminished, 
the  field  changes  correspondingly. 

Assume  a  straight  bar  electro-magnet  in  cir- 
cuit, so  that  a  current  can  be  made  intermit- 
tent, say,  once  a  second.  When  the  circuit  is 
closed  and  the  magnet  is  made,  the  field  at  once 
is  formed,  and  travels  outwards  at  the  rate  of 
186,000  miles  per  second.  When  the  current 
stops,  the  field  adjacent  is  destroyed.  Another 


THE  MAGNETIC  FIELD  Ilg 

closure  develops  the  field  again,  which,  like 
the  other,  travels  outwards  ;  and  so  there  may 
be  formed  a  series  of  waves  in  the  ether,  each 
186,000  miles  long,  with  an  electro-magnetic  an- 
tecedent. If  the  circuit  were  closed  ten  times 
a  second,  the  waves  would  be  18,600  miles 
long  ;  if  186,000  times  a  second,  they  would  be 
but  one  mile  long.  If  400  million  of  millions 
times  a  second,  they  would  be  but  the  forty- 
thousandth  of  an  inch  long,  and  would  then 
affect  the  eye,  and  we  should  call  them  light- 
waves ;  but  the  latter  would  not  differ  from  the 
first  wave  in  any  particular  except  in  length. 
As  it  is  proved  that  such  electro-magnetic 
waves  have  all  the  characteristics  of  light,  it 
follows  that  they  must  originate  with  electro- 
magnetic action  ;  that  is,  in  the  changing  mag- 
netism of  a  magnetic  body.  This  makes  it 
needful  to  assume  that  the  atoms  which  origi- 
nate waves  are  magnets,  as  they  are  experi- 
mentally found  to  be.  But  how  can  a  magnet, 
not  subject  to  a  varying  current,  change  its 
magnetic  field  ?  The  strength  or  density  of  a 
magnetic  field  depends  upon  the  form  of  the 
magnet.  When  the  poles  are  near  together, 
the  field  is  densest ;  when  the  magnet  is  bent 
back  to  a  straight  bar,  the  field  is  rarest  or 
weakest,  and  a  change  in  the  form  of  the  mag- 
net from  a  U-form  to  a  straight  bar  would  re- 


Il6  MODES  OF  MOTION 

suit  in  a  change  of  the  magnetic  field  within  its 
greatest  limits.  A  few  turns  of  wire  wound 
about  the  poles  of  an  ordinary  U-magnet,  and 
connected  to  an  ordinary  magnetic  telephone, 
will  enable  one,  listening  to  the  latter,  to  hear 
the  pitch  of  the  former  loudly  reproduced  when 
the  magnet  is  struck  like  a  tuning-fork  so  as  to 
vibrate.  This  shows  that  the  field  of  the  mag- 
net changes  at  the  same  rate  as  the  vibrations. 

Assume  that  the  magnet  becomes  smaller 
and  smaller,  until  it  is  of  the  dimensions  of  an 
atom;  say,  for  an  approximation,  the  fifty-mil- 
lionth of  an  inch.  It  would  still  have  its  field  ; 
it  would  still  be  elastic  and  capable  of  vibra- 
tion, but  at  an  enormously  rapid  rate  :  but  its 
vibration  would  change  its  field  in  the  same 
way,  and  so  there  would  be  formed  those  waves 
in  the  ether  which,  because  they  are  so  short 
that  they  can  affect  the  eye,  we  call  light.  The 
mechanical  conceptions  are  legitimate,  because 
based  upon  experiments  having  ranges  through 
nearly  the  whole  gamut  as  waves  in  ether. 

The  idea  implies  that  every  atom  has  what 
may  be  loosely  called  an  electro-magnetic  grip 
upon  the  whole  of  the  ether,  and  any  change  in 
the  former  brings  some  change  in  the  latter. 

Lastly,  the  phenomenon  called  induction  may 
be  mechanically  conceived. 

It   is  well  known  that  a  current   in   a  con- 


THE  MAGNETIC  FIELD  \\J 

ductor  makes  a  magnet  of  the  wire,  and  gives 
it  an  electro-magnetic  field,  so  that  other  mag- 
nets in  its  neighborhood  are  twisted  in  a  way 
tending  to  set  them  at  right  angles  to  the  wire. 
Also,  if  another  wire  be  adjacent  to  the  first, 
an  electric  current  having  an  opposite  direction 
is  induced  in  it.  Thus  :  — 

Consider  a  permanent  magnet,  A  (Fig.  16), 
free  to  turn  on  an  axis  in  the  direction  of  the 
arrow.  If  there  be  other  free  magnets,  B  and 
C,  in  line,  they  will  assume  such  positions  that 


S 

[     i 
i     i 

i 

\N 

«5| 

N                            S\ 

N 

u 

^          j      i 

isi 

^A 

Fig.   16. 

their  similar  poles  all  point  one  way.  Let  A 
be  twisted  to  a  position  at  right  angles,  then  B 
will  turn,  but  in  the  opposite  direction,  and  Cin 
similar.  That  is,  if  A  turn  in  the  direction  of 
the  hands  of  a  clock,  B  and  C  will  turn  in  oppo- 
site directions.  These  are  simply  the  observed 
movements  of  large  magnets.  Imagine  that 


Il8  MODES  OF  MOTION 

these  magnets  be  reduced  to  atomic  dimen- 
sions, yet  retaining  their  magnetic  qualities, 
poles  and  fields.  Would  they  not  evidently 
move  in  the  same  way,  and  for  the  same  rea- 
sons ?  If  it  be  true  that  a  magnet  field  always 
so  acts  upon  another  as  to  tend  by  rotation  to 
set  the  latter  into  a  certain  position  with  refer- 
ence to  the  stress  in  that  field,  then,  wherever 
there  is  a  changing  magnetic  field,  there  tJic 
atoms  are  being  adjusted  by  it  to  new  positions. 

Suppose  we  have  a  line  of  magnetic  needles 
free  to  turn,  hundreds  or  thousands  of  them, 
but  disarranged.  Let  a  strong  magnetic  field 
be  produced  at  one  end  of  the  line.  The  field 
would  be  strongest  and  best  conducted  along 
the  magnet  line,  but  every  magnet  in  the  line 
would  be  compelled  to  rotate ;  and  if  the  first 
were  kept  rotating,  the  rotation  would  be  kept 
up  along  the  whole  line.  This  would  be  a  me- 
chanical illustration  of  how  an  electric  current 
travels  in  a  conductor.  The  rotations  are  of 
the  atomic  sort,  and  are  at  right  angles  to  the 
direction  of  the  conductor. 

That  which  makes  the  magnets  move  is  in- 
ductive magnetic  ether  stress,  but  the  advan- 
cing motion  represents  mechanical  energy  of 
rotation  ;  and  it  is  this  motion,  with  the  result- 
ing friction,  which  causes  the  heat  in  a  con- 
ductor. 


ELECTRICAL    ACTION  119 

What  it  is  proper  to  emphasize  is,  that  the 
action  in  the  ether  is  not  electric  action,  but 
more  properly  the  result  of  electro-magnetic 
action.  Whatever  name  be  given  to  it,  and 
however  it  comes  about,  there  is  no  good  rea- 
son for  calling  any  kind  of  an  ether  action  elec- 
trical. 

Electrical  action,  like  magnetic  action,  begins 
and  ends  in  matter.  It  is  subject  to  transfor- 
mations into  thermal  and  mechanical  actions, 
also  into  ether  stress,  —  right-handed  or  left- 
handed —  which,  in  turn,  can  similarly  affect 
other  matter,  but  with  opposite  polarities. 

In  his  Modern  Views  of  Electricity,  Professor 
O.  J.  Lodge  warns  us,  in  a  way  I  quite  approve, 
that  perhaps,  after  all,  there  is  no  such  thing 
as  electricity,  —  that  electrification  and  electric 
energy  may  be  terms  to  be  kept  for  conve- 
nience ;  but  if  electricity,  as  a  term,  be  held 
to  imply  a  force,  a  fluid,  an  imponderable,  or 
a  thing  which  could  be  described  by  some  one 
who  knew  enough,  then  it  has  no  degree"  of 
probability,  for  spinning  atomic  magnets  seem 
capable  of  developing  all  the  electrical  phe- 
nomena we  meet.  It  must  be  thought  of  as  a 
condition  and  not  as  an  entity. 


This  book  is  DUE  on  the  last  date  stamped  below 

OCT  3 1  1931 

8  1939 

MAR  3  0  1939 

(930 
23  1943 
18 1960 


Form  L-9-35m-8,'28 


!»«... 

A     000  933  144 


QC 


UNIVERSITY  of  CALIFORNIA 

AT 

LOS  ANGELES 
LIBRARY 


